US Capitol Police say officers arrested seven unauthorised people in a congressional office building on Thursday night (local time) and charged them with unlawful entry.
The people identified themselves as being affiliated with CBS' Late Show with Stephen Colbert, a person familiar with the matter told The Associated Press.
Another person familiar with the matter provided the AP with a list of nine people who had been stopped by Capitol Police. They included several producers, along with Robert Smigel, the voice behind Triumph the Insult Comic Dog.
The two people who spoke with the AP could not discuss details of the investigation publicly and spoke on condition of anonymity.
The incident Thursday night followed the third public hearing by the House panel investigating the 2021 Capitol insurrection.
Capitol Police said they received a call about a disturbance in the Longworth House Office Building around 8.30pm (Washington time).
"Responding officers observed seven individuals, unescorted and without Congressional ID, in a sixth-floor hallway," the agency said in a 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."
In a statement to The Hollywood Reporter, CBS said the production team was at the Capitol on Wednesday and Thursday (local time) to record a comedy segment featuring Triumph.
"Their interviews at the Capitol were authorised and pre-arranged through Congressional aides of the members interviewed," the network said.
"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."
The USCP statement said the case remains "an active criminal investigation, and may result in additional criminal charges." Capitol Police, departing from standard practice, refused to provide the names of the people who were arrested.