DISTRICT OF COLUMBIA — Cole Tomas Allen appeared Monday in the U.S. District Court for the District of Columbia to face federal charges in connection with an alleged attempt to assassinate President Donald Trump at the White House Correspondents' Dinner. Magistrate Judge Matthew Sharbaugh ordered Allen held pending a detention hearing Thursday.

Allen, 31, appeared on a criminal complaint rather than an indictment and was not asked to enter a plea. He faces three federal counts: attempting to assassinate the president, transportation of a firearm in interstate commerce, and discharge of a firearm during a crime of violence.

According to the Metropolitan Police Department, Allen approached a Secret Service checkpoint at the Hilton on Saturday night armed with a shotgun, a handgun, and multiple knives. Secret Service agents intercepted him before he could reach the ballroom where Trump was preparing to speak. Witnesses reported hearing several shots outside the ballroom.

Investigators said the gunman planned to assassinate the U.S. president and multiple top officials when he tried to storm the gala dinner. Secret Service agents moved Trump and Vice President JD Vance off the stage and rushed the president out of the hotel ballroom, detaining the suspect at the scene after a brief exchange of gunfire.

One Secret Service agent was hit by gunfire but was protected by his bulletproof vest. Trump later told reporters the agent was unharmed. The president also posted surveillance footage of the suspect attempting to sprint past a checkpoint.

Allen was taken to a hospital for evaluation following his arrest, said Jeffery Carroll, interim chief of the Metropolitan Police Department. Carroll characterized Allen as a "lone actor."

Allen emailed his family a manifesto roughly 10 minutes before the shooting, which mocked the Hilton hotel's security procedures. In social media posts before the alleged assassination attempt, Allen described Trump as a sociopathic mob boss and a villain.

Allen is a Caltech-trained mechanical engineer with a master's degree in computer science from California State University, Dominguez Hills. He tutored part-time at a test-preparation company in Torrance, California, and built independent video games on the side. The White House Correspondents' Association, which hosts the dinner, is an independent nonprofit of journalists and is not a White House organization.