This story will be updated as new information comes in.
CHATTANOOGA -- The latest on the Chattanooga shootings (all times local):
A federal law enforcement official says authorities are continuing to search the computer belonging to the gunman who killed four Marines in Chattanooga, but as of Friday morning, haven't found an extensive online presence.
The official says they also haven't uncovered evidence suggesting Muhammad Youssef Abdulazeez was directly inspired by the Islamic State militant group. But the official says the review is continuing.
The official, who asked not to be identified, did not mention any other terrorist-related groups. The official insisted on anonymity because they were not authorized to speak publicly since the investigation is still in progress.
Authorities say Abdulazeez opened fire Thursday at a military recruiting center and another military site before his own death.
The 24-year-old man who authorities say attacked two military facilities Thursday in Chattanooga and killed four Marines is believed to have been arrested for drunken driving in April.
A booking report and mug shot from Hamilton County shows a Mohammad Youssduf Adulazeer was charged with first offense drunken driving on April 20 and arrested by the Chattanooga Housing Authority. His age and address match the suspect of the man authorities say attacked the military facilities, though the spelling of his name is slightly different from Muhammad Youssef Abdulazeez. Federal authorities and public records have given several spellings of the name.
The online booking report doesn't give the status of the case, saying only that he was charged.
The suspect in the fatal shooting of four marines is a graduate of the University of Tennessee at Chattanooga.
University spokesman Mike Andrews said 24-year-old Muhammad Youssef Abdulazeez graduated in 2012 with a bachelor's degree in electrical engineering. The Tennessee Valley Authority confirmed that he also was a student intern a few years ago at the authority, a federally owned utility that operates power plants and dams across the South.
Hussnain Javid is a 21-year-old senior at the university. Javid said Abdulazeez studied electrical engineering at the same college and that they both graduated from Red Bank High School in Chattanooga several years apart. Javid said Abdulazeez was on the high school's wrestling team and was a popular student.
Javid said Abdulazeez was "very outgoing" and that he was well known.
The U.S. National Counterterrorism Center said it has seen nothing so far to connect Abdulazeez to any terrorist organization.
A U.S. official says Abdulazeez is believed to have been born in Kuwait, but it was unclear whether he was a U.S. or Kuwaiti citizen. The official spoke on condition of anonymity to discuss the ongoing, sensitive investigation.
Associated Press writer Ted Bridis contributed to this report.
A United States official says there's no indication that the suspected Chattanooga gunman was under investigation by the FBI or on the radar of federal law enforcement at the time of the shooting.
The official was briefed on the investigation but was not authorized to discuss an ongoing investigation and spoke on condition of anonymity.
The FBI says the gunman opened fire Thursday at a recruiting center and another U.S. military site a few miles apart, killing at least four Marines.
A U.S. official speaking on condition of anonymity identified the gunman as 24-year-old Muhammad Youssef Abdulazeez of Hixson, Tennessee, though the exact spelling of his first name was in dispute, with federal authorities and records giving at least four variations.
Associated Press reporter Eric Tucker contributed to this report.
Attorney General Loretta Lynch says she's directing the FBI to take the lead on a "national security" investigation into the Chattanooga attacks.
In a statement Thursday, she said the two shootings at military sites in Chattanooga represented a "heinous attack."
The shooting at a recruiting center and another U.S. military site a few miles away killed four Marines.
The attacker is also dead.
Federal authorities have not identified a motive but have said they are investigating the possibility it was an act of terrorism.
The U.S. National Counterterrorism Center is reporting no apparent nexus to terrorism has been uncovered in the investigation of the fatal shootings in Tennessee, but intelligence officials are monitoring the investigation closely.
It also says there has been no credible claim of responsibility so far for anyone who might have influenced the gunman, who also was killed.
Those details were in a report the counterterrorism center circulated Thursday evening to U.S. law enforcement agencies. The Associated Press reviewed the report.
Even though the report says there was no connection uncovered so far to terrorism, it described efforts by the Islamic State group to revitalize homegrown extremists to conduct physical attacks inside the United States.
Navy Secretary Ray Mabus is expressing condolences for four Marines killed in shootings in Tennessee. He called the victims "four heroes."
Maybus says "the tragedy in Chattanooga is both devastating and senseless."
The Marines were killed at the Navy Operational Support Center, often referred to as a "reserve center." It's used by both Navy and Marine personnel to provide training and readiness support for reserve components to support the services. The Navy maintains 123 such facilities across the United States and its territories.
Democratic presidential candidate Hillary Rodham Clinton has described the shootings as an episode of "senseless violence" that she linked to other recent mass shootings.
"It's terrible when we lose Marines anywhere in the world. But to lose four in Chattanooga, Tennessee is just heartbreaking," she told reporters after holding her first town hall event in New Hampshire.
Authorities and officials say the Marines were killed in two separate attacks at military facilities in Chattanooga.
"I hope that we can find a way to stop this kind of violence that is stalking our children and people in study and people who wear the uniform of our country," Clinton said.
President Barack Obama is promising a thorough and prompt investigation into the attack at two military sites that killed at least four Marines in Chattanooga.
Obama says it appears the attack was committed by a lone gunman, but that a full investigation is ongoing.
The president is calling the shooting a "heartbreaking circumstance." He says he's been briefed about the incident and has been in touch with the Defense Department to make sure military facilities are vigilant.
Obama spoke in the Oval Office just minutes after returning to Washington from a trip to Oklahoma. He was joined his counterterrorism and homeland security adviser and the FBI director.
Vice President Joe Biden says the United States will get to the bottom of the shootings that killed at least four Marines in Chattanooga.
Biden says the young Marines killed were part of what he's calling "probably the most incredible generation that this country has seen." He's pointing out that more than 4 million Americans have signed up for military service since 9/11, even though they knew they'd almost certainly be put in harm's way.
Biden says the families of those troops have already given a lot to the country.
Biden is asking Americans to keep the families of the victims in their prayers.
The vice president was speaking at a summit of liberal activists in Washington.
Law enforcement swarmed the house believed to belong to the man authorities say killed four Marines and wounded others in two attacks on military facilities.
An Associated Press reporter saw officers with weapons drawn at the house and two females were led away in handcuffs. It's not clear who these females are.
The law enforcement presence came shortly after a news conference in which officials described the attacks.
A U.S. official says the gunman in the shootings in Tennessee has been identified as 24-year-old Muhammad Youssef Abdulazeez.
He was believed to have been born in Kuwait, and it was unclear whether he was a U.S. or Kuwaiti citizen. The official was speaking on condition of anonymity to discuss the ongoing, sensitive investigation. It was not immediately clear whether the gunman's first name was spelled Muhammad or Mohammad.
He is from Hixson, Tennessee, which is just a few miles across the river from Chattanooga.
Authorities and officials say the gunman killed four Marines and wounded a police officer and others in two attacks on military facilities. The gunman was also dead.
Associated Press writer Ted Bridis in Washington contributed to this report.
The Chattanooga mayor says the killings of four military personnel during an attack on two facilities in the city are "incomprehensible."
Mayor Andy Berke said at a news conference Thursday that the shooter had also been slain. He didn't say how. A police officer and others were also wounded in the attacks.
"I want to say again, it is incomprehensible to see what happened and the way that individuals who proudly serve our country were treated," he said. "As a city, we will respond to this with every available resource we have."
A U.S. attorney says the killing of four people during a shooting rampage in Chattanooga is an "act of domestic terrorism."
U.S. Attorney Bill Killian made the comments Thursday during a news conference. Mayor Andy Berke says two different military sites were "viciously attacked." The shooter was killed at a Naval reserve center, where the victims were also slain.
There was also a shooting at a military recruitment center about 7 miles away.
The death toll in the Chattanooga shootings includes four U.S. Marines and the sole gunman believed responsible, a U.S. official told The Associated Press, speaking on condition of anonymity to discuss an ongoing investigation.
The official said two others, a soldier and a police officer, were wounded.
The shootings happened at two military facilities in Chattanooga on Thursday, sending troops scrambling for safety.
Associated Press writer Ted Bridis in Washington contributed to this report.
Tennessee Gov. Bill Haslam says people serving their country have lost their lives in the attacks on two military facilities there.
Haslam did not say how many people were killed or provide further details about who was among the dead on Thursday.
Chattanooga police say the active shooting is over, but they have not said what happened to the suspect or suspects.
Mayor Andy Berke said earlier at a news conference that there was "an officer down" at a military reserve center.
An active duty Army recruiter in Chattanooga says he was at his office when someone opened fire and he heard 30 to 50 shots.
Sgt. 1st Class Robert Dodge, 36, was working at the Armed Forces Career Center off Lee Highway. There are also offices for Air Force, Navy and Marine Corp there.
"We heard one single shot, which kind of sparked our attention. Shortly after that, just a few seconds, the shooter began shooting more rounds. We realized it was an actual shooting, so we then initiated our active shooter drill: getting down low to the ground, moving to a safe location. And we waited until everything seemed to be clear."
He said he did not see the shooter or a vehicle.
Chattanooga police say the active shooting is over, but they have not said what happened to the shooter.
President Barack Obama has been briefed by his national security team on the shooting involving two military sites in Tennessee.
White House spokesman Eric Schultz says that the president will continue getting updates from his staff as needed.
Chattanooga police say the active shooter situation is over, but they have not said what happened to the suspect or suspects.
Obama was in Oklahoma to speak about criminal justice reform at a federal prison at the time of the shooting. He plans to return to Washington on Thursday afternoon.
Shootings have been reported at two locations in Chattanooga.
One of them took place at the Armed Forces Career Center off Lee Highway. Television images of a door to the center in a strip mall showed more than a dozen bullet holes in the glass.
About 7 miles away, another shooting happened at the Navy Operational Support Center and Marine Corps Reserve Center.
That center sits between the highway and a pathway that runs through Tennessee RiverPark, a popular park at a bend in the Tennessee River northeast of downtown Chattanooga. It's in a light industrial area that includes a Coca-Cola bottling plant and Binswanger Glass.
The two entrances to the fenced facility have unmanned gates and concrete barriers that require approaching cars to slow down to drive around them.
Police say the active shooting situation is over, but there is no word what happened to the suspect or suspects.
Chattanooga police say the active shooting that apparently took place at two military facilities is now over, but there is no word yet on what happened to the suspect or suspects.
Police said in a tweet: "Active shooter situation is over. Details forthcoming."
Chattanooga Mayor Andy Berke said earlier at a news conference that it was a "very terrible situation." He did not release any other details. Berke said there's "an officer down" at a military reserve center.
It was not immediately clear how many people may have been hurt, or how many shooters may have been involved.
A woman who says she witnessed the shooting in Chattanooga says she heard a barrage of gunfire near one of the shooting sites.
"It was rapid fire, like pow pow pow pow, so quickly. The next thing I knew there were police cars coming from every direction," said Marilyn Hutcheson, who works at a Binswanger Glass.
Chattanooga Mayor Andy Berke said at a brief news conference that police were pursuing an active shooter and there was an officer down.
Hutcheson says she ran inside, where she remains with other employees and a customer. The gunfire continued with occasional bursts she estimated for 20 minutes.
"We're apprehensive," Hutcheson said. "Not knowing what transpired, if it was a grievance or terroristic related, we just don't know."