At least 58 people were killed and 515 others wounded when a gunman opened fire on concertgoers at an outdoor show on the Las Vegas Strip Sunday night, police said.

Police have been saying they believe more than 50 were killed throughout the morning, but provided a more specific number shortly before 9 a.m. Las Vegas time.

"Right now we are using the number of 58," Clark County Sheriff Joseph Lombardo told reporters. "I just was informed that it may be 59 of an individual that may have expired at Sunrise Hospital ... The number of injured, we are using the number of 515."

"We will be in a long process of body recovery out there and evidence recovery and evidence documentation," Lombardo added. "It's a long, laborious process to identify the victims and reunite them with the family members to advise them of their situation."

Law enforcement identified 64-year-old Stephen Craig Paddock, a white male from Mesquite, Nev., as the man who rained gunfire on the Route 91 Harvest country music festival from his hotel room on the 32nd floor of the Mandalay Bay Hotel at approximately 10:08 p.m. Sunday. Witnesses have said the shooting lasted between 10 and 20 minutes.

The Las Vegas Metropolitan Police Department said SWAT officers responding to the call breached the hotel room and found Paddock dead.

The FBI is investigating the attack with local law enforcement. Agents executed search warrants of Paddock's Mesquite residence and the hotel room. The hotel's 32nd floor remains closed to the public and press.

The FBI is trying to get a search warrant for an additional property Paddock owned in northern Nevada.

The Islamic State claimed responsibility for the massacre, saying the shooter converted to Islam several months ago, but did not offer any proof for the claim.

"As this event unfolds, we have determined to this point no connection with an international terrorist group. As this investigation continues, we will continue to work with our partners to ensure that this is factually, thoroughly, and absolutely investigated to be able to bring comfort and peace back to the community," said Aaron Rouse, the special agent in charge of the FBI's Las Vegas bureau.

Speaking from the White House, President Trump called the shooting "an act of pure evil."

Concertgoers captured video of the chaos as gunfire cut through the crowd.

Police also released audio of the police conversation as they breached the room of the suspected shooter.

The shooting is the largest deadly mass shooting to take place in modern U.S. history. Forty-nine people died and more than 50 others were injured in the 2016 attack at the Pulse nightclub in Orlando.

By 3:30 a.m. Pacific time Monday, police said they were "confident, but not 100 percent sure" they had located Marilou Danley, a woman they believed resided with Paddock and who they had been seeking earlier.