Robert Smigel, who voices Triumph the Insult Comic Dog, was among the Late Show staff arrested.

A group of staffers for CBS' The Late Show With Stephen Colbert was arrested Thursday night in the U.S. Capitol and charged with illegal entry while filming a sketch with Triumph the Insult Comic Dog.

Former Saturday Night Live writer Robert Smigel, who voices Triumph, was among those detained in the Longworth House Office Building after being closed to visitors.

"On Wednesday, June 15, and Thursday, June 16, Triumph the Insult Comic Dog was on-site at the Capitol with a production team to record interviews for a comedy segment on behalf of The Late Show," CBS says in a statement to EW.

"Their interviews at the Capitol were authorized and pre-arranged through Congressional aides of the members interviewed," the statement continues. "After leaving the members' offices on their last interview of the day, the production team stayed to film stand-ups and other final comedy elements in the halls when they were detained by Capitol Police."

In a statement provided to EW, U.S. Capitol Police say they arrived at the building after receiving a call for a disturbance. "Responding officers observed seven individuals, unescorted and without Congressional ID, in a sixth-floor hallway," adds the statement. "The building was closed to visitors, and these individuals were determined to be a part of a group that had been directed by the USCP to leave the building earlier in the day."

Capitol police say they are conducting a criminal investigation that "may result in additional criminal charges after consultation with the U.S. Attorney."

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