A 20-year-old Pennsylvania man was suspected to have been the gunman who attempted to assassinate former President Donald Trump on Saturday, firing several shots and killing at least one spectator, federal and local law enforcement agencies said.

The FBI early on Sunday identified the suspect, who was killed at the scene, as Thomas Matthew Crooks, of Bethel Park.

Shots rang out a few moments after Trump stepped onto an outdoor stage in Butler, Pennsylvania, at about 6 p.m. on Saturday, State Police Lt. Col. George Bivens said. The suspect was firing from the roof of a building outside the security perimeter, taking aim from hundreds of feet away from the stage, law enforcement said.

One of the bullets struck Trump in his right ear, the former president said. The U.S. Secret Service said Trump was “safe.”

A Secret Service counter-sniper opened fire and killed the suspect, the agency said. The scene was “chaotic” and “everything unfolded very quickly,” Bevins said.

Law enforcement officials took several hours to publicly identify Crooks as their suspect, saying at a press conference late Saturday that they believed they knew who carried out the shooting, but were refraining from naming the individual.

Officials had said during that press conference that they were using the suspect’s DNA to confirm his identity, because the suspect had not been carrying anything that would have identified him.

“It’s a matter of doing biometric confirmations,” FBI Special Agent in Charge Kevin Rojek said. “So, there was no identification on the individual, for example, so we’re looking at photographs right now and we’re trying to run his DNA and get biometric confirmation.”

It was too early in the investigation to say whether Crooks had been acting alone, Bivens said. Investigators were determining if anyone else had been involved, he said.

The FBI did not “currently have an identified motive, although our investigators are working tirelessly to attempt to identify what that motive was,” Rojek said.

Crooks had been registered as a Republican voter, according to Pennsylvania state records.

As the FBI issued a statement early Sunday naming Crooks, a bureau spokesperson said the investigation remains “active and ongoing.” The FBI urged anyone with photos, videos or information to come forward.

ABC News’ Jack Date, Luke Barr, Isabella Murray, Mark Osborne and Charlotte Slovin contributed to this report.