One arrest was made for assault on an officer Wednesday night outside of the Democratic National Committee in Washington, D.C., according to Capitol Police.

Capitol Police said they had to “keep back” 150 people who were “illegally and violently” protesting.

Six officers sustained injuries from encounters with the demonstrators, “ranging from minor cuts to being pepper sprayed to being punched,” according to Capitol Police.

All officers were treated on the scene, a law enforcement source confirmed to ABC News.

Members of Congress were hearing from prospective candidates inside of the DNC when Capitol Police evacuated them from the building, Congressman Brad Sherman, D-Cailf. told ABC News in a phone interview.

In total, about seven members of Congress were inside when they were evacuated from the building by “heavily armed and serious” U.S. Capitol Police officers, Sherman said.

The forum was attended by Democratic leadership, including minority leader Hakeem Jeffries, Whip Katherine Clark and Pete Aguilar, but Sherman said Jefferies and Clark had left by the time protests started breaking out.

Rep. Sherman said members inside the room heard chants of “cease-fire now,” and they thought it was going to be 10 or 15 minutes and then the protesters were going to leave.

“Then the Capitol Police came in big time and said, ‘We’re getting you out of here,'” he told ABC News.

Congressman Sean Casten, D-Ill., posted on X he was evacuated from the Democratic Congressional Campaign Committee office after the building was surrounded by protesters.

“I was just evacuated from the @dccc office after the building was surrounded by protestors who had blocked all modes of ingress and egress. Grateful to Capitol Police for getting all members and staff out safely. To the protestors: PLEASE don’t do something irresponsible,” said Rep. Casten.

“We did not come out here to fight or to be violent. The violence happened to us as soon as we got out here,” Jessica Anderson told ABC News affiliate, WJLA.

Calling the protesters violent was a “complete mischaracterization,” Anderson said. “We did not expect the hostility we got.”

Capitol Police tweeted that the group had cleared out shortly after 10 p.m., but officers were staying on the scene “out of an abundance of caution.”

PHOTO: Police officers wear gas masks as they keep watch outside the Democratic National Headquarters during a demonstration calling for a ceasefire, in Washington, D.C., on Nov. 15, 2023.
Police officers wear gas masks as they keep watch outside the Democratic National Headquarters during a multi-denominational event hosted by the Democratic Socialists of America, IfNotNow Mo…Leah Millis/Reuters