LAS VEGAS (AP) - Authorities hunting for a motive behind the carnage at a Las Vegas concert are looking into the possibility that gunman Stephen Paddock planned additional attacks, including a car bombing.
In addition, law enforcement was investigating whether Paddock had scoped out other music festivals in Las Vegas and Chicago - and even Boston's Fenway Park.
Las Vegas police also announced Thursday that they had found a vehicle they had been searching for as part of the investigation into the massacre that left 58 people dead and nearly 500 injured Sunday at an outdoor country music festival.
More about the deadliest mass shooting in modern U.S. history:
A federal official told The Associated Press that authorities are examining whether Paddock planned more attacks , such as a car bombing. The official wasn't authorized to discuss the matter publicly and spoke on condition of anonymity.
Authorities previously disclosed Paddock had 1,600 rounds of ammunition in his car, along with fertilizer that can be used to make explosives, and 50 pounds of Tannerite, a substance used in explosive rifle targets.
Authorities also revealed that Paddock booked rooms overlooking the Lollapalooza festival in Chicago in August and the Life Is Beautiful show near the Vegas Strip in late September. Investigators also came across mention of Fenway, Boston police Lt. Detective Mike McCarthy said, though he provided no further details.
In addition, police announced they had located a Hyundai Tucson while executing a search warrant at the home in Reno, Nevada, that Paddock shared with his girlfriend, Marilou Danley. It wasn't immediately clear if the car was found on Thursday or earlier in the week when police searched the home and found several guns and ammunition.
NRA PROPOSES REGULATIONS
The National Rifle Association is joining the Trump administration and top congressional Republicans in a surprise endorsement of a narrow gun restriction in the wake of the Vegas concert shooting.
The NRA said devices called "bump stocks" that allow semi-automatic rifles to perform more like fully automatic weapons should be "subject to additional regulations." The devices were found in Paddock's hotel room.
President Donald Trump said his administration is considering whether they should be banned.
The NRA, which famously opposes virtually any hint of new restrictions, dismissed calls from some Democrats for more gun control, however. The organization's leaders said, "Banning guns from law-abiding Americans based on the criminal act of a madman will do nothing to prevent future attacks."
THE UNWITTING FIRST RESPONDERS
A group of firefighters driving back to their Vegas station after responding to a call for a minor car crash ended up being the first to respond to the shooting massacre.
Brian Emery recalled Thursday that gunfire rang out as hundreds of hysterical people swarmed the vehicle on the Las Vegas Strip.
It was pure coincidence that the Clark County Fire Department crew members on Engine 11 were the first on-duty emergency personnel to arrive at Sunday's shooting.
The surge of people forced Emery to stop driving, but he eventually inched the engine out and got it to a parking lot where the crew could start treating patients. The work continued until after sunrise.
58 WOODEN CROSSES
White crosses have been placed on the Las Vegas Strip for each victim of the concert shooting.
Retired carpenter Greg Zanis drove nearly 2,000 miles from the Chicago area to put up the 58 crosses Thursday afternoon.
The 66-year-old is known for installing the markers at the sites of other mass killings, including the Columbine and Sandy Hook school shootings and Orlando nightclub massacre.
He plans to keep the tribute up for 40 days before giving the crosses to the families of the victims.
Thousands gathered Thursday to mourn a police officer who was one of the 58 people.
A candlelight vigil was held Thursday in honor of shooting victim Denise Burditus on the football field of the Hedgesville, West Virginia, high school she graduated from in 1985.
Burditus, 50, had posted a photo on Facebook earlier Sunday of herself and her husband standing in front of the stage at the Vegas concert. Her husband later posted on his Facebook page that the mother of two died in his arms.
In other tributes, NFL fans held up their phones to shine flashlights during a moment of silence for the shooting victims before a game in Florida on Thursday between the Tampa Bay Buccaneers and the New England Patriots.