Jeanine Pirro, US attorney for the district of Columbia, said on X that the security footage also showed suspect Cole Allen “casing the area” in the Washington Hilton during the day before Saturday’s attack at an annual media gala in the capital.

The nearly six-minute video features several clips of a man walking back and forth down a corridor, and through a fitness centre.

A more dramatic excerpt shows the man, carrying what appears to be a long-barreled gun, charging through a security checkpoint past uniformed police and agents in suits.

Pirro said the video shows “Cole Allen shoot a US Secret Service officer during his attempt to assassinate the President at the White House Correspondents’ Dinner.”

“There is no evidence the shooting was the result of friendly fire,” she said, adding that the video had already been provided to the US district court.

The footage appears to show a Secret Service agent discharging his weapon three times in the direction of the assailant, although police have stressed that Allen was not shot during the attack.

In a slow-motion clip released by the justice department, white circles are placed around one agent’s weapon at the three moments in which muzzle blasts are seen from the firearm.

Allen, 31, was tackled and detained in a chaotic scuffle with security guards. Shots were fired but no one was killed.

His capture does not feature in the video released Thursday, and it was not immediately clear from the footage who was shot.

Allen, from the state of California, was charged in court Monday with trying to assassinate the Republican president. He faces up to life in prison if convicted.