Update at 12:47 p.m.: lockdown has been lifted at Chattanooga State, campus has returned to regular schedule following "all clear" from police.
All available Chattanooga police have responded to reports of shots fired near the U.S. Naval and Marine Reserve Center on Amnicola Highway, the site where Mohammad Youssef Abdulazeez opened fire on July 16, killing five U.S. servicemembers.
Despite the calls, police have yet to find evidence of a shooter or find anyone who has seen a shooter, and Chief Fred Fletcher says he believes there is no threat to the public. Still, police have responded out of an "abundance of caution," he said.
"What we have is a short time ago we received two reports of what appears to be a sound like the report of a single gunshot," Fletcher said. "We are responding to make sure that those were not threats to the community. Again, nobody's seen a gun, nobody's seen anybody with a weapon . . . We are responding, given the nature of the location, more robustly than we normally would."
Both 911 calls were placed around 10:25 a.m. The other call indicated that at least one shot was fired at the nearby Chattanooga State Community College, which was on lockdown. Absences will not count against attendance, the college said.
In an earlier tweet told students that "if you are on campus in your car now, either leave campus or call security to be escorted into a building," and in another tweet told students to "stay indoors."
Civilians were cleared out of the park and the area around the reserve, which is part of the Tennessee Riverwalk that also serves as a boat entrance to the Tennessee River.
Officers also responded to the Lee Highway recruitment office where Abdulazeez began his deadly shooting spree this summer, though there are no reports of shots fired at that location.
There were about 30 officers on scene at the naval center at Amnicola Highway just before noon and more than a dozen squad cars. Police patrolled the area armed with automatic rifles. Police said the main building was secure shortly after the call went out.
Police have also responded to other "at-risk" locations that Fletcher said he is not willing to disclose.
False reports of shootings are not uncommon. During the July 16 shootings, officers responded to a report of a shooting at Bradley Square Mall that turned out to be false.
There have also been reports of a SWAT on Frazier Avenue, but that incident is unrelated, Fletcher said.
Read more about the July 16 attacks here.