WASHINGTON — A pellet from a Mossberg pump-action shotgun fired by Cole Tomas Allen struck the bullet-resistant vest of a Secret Service officer during an attack at a Washington hotel hosting the White House Correspondents' Association dinner on April 25, federal prosecutors said. The officer survived, and Allen was injured during the attack but was not shot.

Allen ran through security with a long gun toward the ballroom of the media gala, according to authorities. U.S. Attorney for the District of Columbia Jeanine Pirro posted a video on social media showing the moment that authorities say a man with guns and knives attempted to storm the event.

Pirro said laboratory analysis tied the projectile recovered from the officer's vest to Allen's weapon. "We now can establish that a pellet that came from the buckshot from the defendant's Mossberg pump-action shotgun was intertwined with the fiber of the vest of the Secret Service officer," she said.

"It is definitively his bullet," she said. Pirro said there was no evidence the agent had been hit by friendly fire.

Allen has been charged with attempted assassination of the president and two additional firearms counts, including discharging a weapon during a crime of violence. He faces up to life in prison if convicted of the assassination count alone. He remains behind bars pending trial.

Allen, 31, is from Torrance, California. He worked as a part-time tutor for a test preparation company and is an amateur video game developer. A phone call to lawyers representing Allen went unanswered on Sunday.