The FBI's Washington Field Office is responding to the incident and providing support at the U.S. Capitol, according to a statement.
One of the two police officers hit by a auto ramming into barriers surrounding the U.S. Capitol complex on Friday afternoon was pronounced dead, Acting Chief of Capitol Police Yogananda Pittman said.
US Capitol Police said that one of the police officers had also died, while the other two officers are hospitalised. The suspect, who was shot by police, also died. A senior law enforcement official confirmed to The Daily Beast that Green was the suspect, though he has not yet been officially identified by police.
Green described himself as a follower of the Nation of Islam and its founder, Louis Farrakhan, and spoke of going through a hard time where he leaned on his faith, according to recent messages posted online that have since been taken down. The authorities have not yet confirmed the suspect's identity or specified a motive.
Both Capitol Police officers were taken to the hospital, with one of the officers dying as a result of undisclosed injuries, officials said.
Capitol Police have said the suspect was taken into custody. The White House said President Joe Biden is aware of the incident, and was not in the area at the time.
The US Capitol complex was placed on lockdown after the shooting and staff were told they could not enter or exit buildings.
Capitol Police said that someone rammed a vehicle into two of its officers.
Capitol police officials said the driver rammed their auto into a barricade along Constitution Avenue.
The gunfight reportedly occurred near the Capitol complex's north barricade. "The suspect rammed his auto into two of our officers and then hit the north barricade barrier", Pittman said. The attacker reportedly exited the vehicle to stab an officer with a knife.
"Capitol Police officers heroically defended our Capitol when it was under attack yet again, and I am deeply grateful for their service", Moulton said. "At this time, the suspect has been pronounced deceased". "Officer Evans had been a member of the United States Capitol Police for 18 years".
Capitol Police and National Guard troops were called upon soon afterward to secure the Capitol during Biden's inauguration and faced another potential threat in early March linked to conspiracy theories falsely claiming Trump would retake the presidency. He said there did not appear to be any indication the attack was terrorism-related, but the investigation is ongoing and investigators will continue to see if there's any links to terrorism.
But permanent barriers remain in place on all the roadway entrances to the Capitol, well-manned by police and national guard.