Who was the gunman who tried to assassinate Donald Trump?

The FBI has named Thomas Matthew Crooks, 20, of Bethel Park, Pennsylvania, as the man they believe shot of former US President Donald Trump. The town is about an hour's drive away from the rally that Trump was addressing.

Secret Service agents then shot Crooks dead as he lay on the roof of a building just outside the rally venue at a farm show in Butler, Pennsylvania, the agency said.

One attendee was also killed and two spectators were critically injured, authorities said. All were identified as men.

Media reports in the US say Crooks was registered as a Republican in Allegheny County, Pennsylvania, according to county voter records.

But US federal campaign-finance records also show that Crooks donated about 14 euros to the Progressive Turnout Project, a liberal group that encourages Americans to vote.

According to the USA Today newspaper he doesn't have a criminal record in Pennsylvania.

A video posted to social media and geolocated by the AP shows the body of a person wearing grey camouflage lying motionless on the roof of a building at AGR International Inc., a manufacturing plant just north of the Butler Farm Show grounds where Trump’s rally was held.

Officials said members of the U.S. Secret Service counterassault team killed the shooter. The heavily armed tactical team travels everywhere with the president and major party nominees and is meant to confront any active threats while other agents focus on safeguarding and evacuating the person at the centre of protection.

Law enforcement recovered an AR-style rifle at the scene, according to a third person familiar with the matter who spoke on condition of anonymity to discuss the ongoing investigation.

An AP analysis of more than a dozen videos and photos from the scene of