Officer Brian Sicknick died of injuries suffered when supporters of President Trump swarmed the legislative building, the Capitol Police said, bringing to five the number dead from the riot.

Officer Brian D. Sicknick died at about 9:30 p.m. on Thursday, the Capitol Police said in a statement. He had been with the agency since 2008.

Mr. Sicknick was responding to the riots on Wednesday and “was injured while physically engaging with protesters,” the agency’s statement said, although officials didn’t immediately elaborate on the nature of his injuries or how he interacted with the crowd. After sustaining the injuries, Mr. Sicknick returned to his division office, collapsed, and was taken to the hospital.

Police said earlier on Thursday that the mob “actively attacked” officers using metal pipes and chemical irritants such as tear gas. More than 50 Capitol and DC police officers were injured in the riot, and several were hospitalized with serious injuries, authorities said.

Two House Democrats who are launching an investigation into Capitol Police’s failures during Wednesday’s attempted coup mourned Sicknick’s death in a statement.

“Our hearts break over the senseless death of United States Capitol Police Officer Brian D. Sicknick, who was injured in the line of duty during yesterday’s violent assault on the Capitol,” Reps. Rosa DeLauro and Tim Ryan said in a joint statement. “Our prayers are with his family, friends, and colleagues on the force … To honor Officer Sicknick’s memory, we must ensure that the mob who attacked the People’s House and those who instigated them are held fully accountable.”

U.S. Capitol Police Officer 'Brian Sicknick' Dies from Injuries sustained during pro Trump protest 1