Alleged WHCD Gunman Cole Allen Charged With Attempting to Assassinate President

The man accused of opening fire just outside the White House Correspondents' Dinner appeared before a judge Monday -- and prosecutors formally hit him with three charges during his arraignment in D.C. federal court ... including attempting to assassinate the president.

Cole Allen -- a 31-year-old teacher from Torrance, California -- was also charged with allegedly transporting a firearm and ammunition with intent to commit a felony ... and discharging a firearm during a crime of violence. He did not enter a plea.

Before Monday's charges, Allen was initially accused of using a firearm during a crime of violence and assaulting a federal officer with a dangerous weapon following Saturday night's terrifying incident at the Washington Hilton.

Authorities say Allen allegedly charged toward the White House Correspondents' Dinner while firing his weapon as he ran toward the ballroom area inside the hotel where it was taking place ... where President Donald Trump, first lady Melania Trump, Vice President J.D. Vance and several members of Trump's cabinet were gathered inside.

The Secret Service says the chaos unfolded near the event’s main security checkpoint and -- according to D.C. Metro Police -- Allen was allegedly armed with a shotgun, a handgun and multiple knives when he was taken into custody.

Investigators are also combing through writings they describe as a manifesto ... documents they say were sent to family members just minutes before the shooting and allegedly outlined plans to target Trump officials. Authorities say the writings referred to Allen as a "Friendly Federal Assassin" and criticized policies tied to the Trump Administration.

U.S. Attorney Jeanine Pirro announced the initial charges -- two counts of using a firearm in a crime of violence, and one count of assault on a federal officer using a dangerous weapon -- Saturday night and later confirmed Allen would be arraigned Monday.

POTUS reacted to the incident Sunday … calling Allen a "sick guy" and saying he appeared deeply troubled.