A Democratic congressman, Jamaal Bowman, acknowledged triggering a fire alarm Saturday in one of the Capitol office buildings as lawmakers scrambled to pass a bill to fund the government before the midnight shutdown deadline.

The fire alarm sounded out around noon in the Cannon House Office Building and prompted a building-wide evacuation at a time when the House was in session and staffers were working in the building. The building was reopened an hour later after Capitol Police determined it was not a threat.

The GOP-controlled House Administration Committee, which oversees issues pertaining to the Capitol complex, posted a picture of a person pulling the fire alarm who appeared to be Mr. Bowman.

The New York lawmaker told reporters hours later that it was a mistake and that he was rushing to get to votes and was trying to get through a door that is usually open, but was closed due to it being a weekend.

“I thought it would help me open the door,” he said about pulling the trigger, denying that it was an effort to stall anything.

At the time of the evacuation House Democrats were working to delay a vote on a 45-day funding bill to keep federal agencies open. They said they needed time to review the 71-page bill that Republicans abruptly released to avoid a shutdown.

The funding package was ultimately approved 335-91 on Saturday afternoon, with most Republicans and almost all Democrats — including Mr. Bowman — supporting the bill.

In a late-night statement, Mr. Bowman said, “I want to be very clear, this was not me, in any way, trying to delay any vote. It was the exact opposite — I was trying urgently to get to a vote, which I ultimately did and joined my colleagues in a bipartisan effort to keep our government open.”

Mr. Bowman said he met with the House Sergeant at Arms and the Capitol Police “at their request, and explained what had happened. My hope is that no one will make more of this than it was.”

Capitol Police said in a statement Saturday that an “investigation into what happened and why continues.”

After the vote, Republicans, including Speaker McCarthy, criticized Mr. Bowman over the fire alarm. Some lawmakers even floated the idea of drafting a motion to expel or censure him from the House.

“This should not go without punishment,” Mr. McCarthy told reporters. “This is an embarrassment.”

He added that he plans to talk with the Democratic leader Hakeem Jeffries of New York to figure out a possible response.

But Mr. Jeffries met with Mr. Bowman shortly after the vote and Mr. Bowman said his fellow New York colleague was “supportive.”

“He understood that it was a mistake and that’s all it was,” he said. Mr. Bowman added that the reaction from McCarthy and other Republicans is dishonest.

“(McCarthy’s) trying to weaponize a mistake of me coming, rushing to get to a vote as something nefarious when it wasn’t,” he said.