Watch: Moment police officer spots Trump rally gunman

The Butler Township Police Department has released bodycam video showing the moments before an assassination attempt on former president and Republican candidate Donald Trump on 13 July.

The footage shows a police officer being hoisted up to a roof near where the attacker is stationed. The unarmed officer quickly jumps down, saying he saw the gunman. He then runs to his vehicle for a firearm.

Minutes later, the footage shows the officer return to the roof. By that time, the gunman had been killed.

Law enforcement, including the Secret Service, have faced questions about how the gunman was able to get access to the rooftop and open fire.

Trump was shot in the ear and one person was killed.