Robert Contee, chief of the DC police department, told a news conference later that there was no longer an ongoing threat and the attack was not believed to be related to terrorism.
In online posts since removed, Green described being under government thought control and said he was being watched.
"We saw the vehicle barriers perform the way they should".
"To be honest these past few years have been tough, and these past few months have been tougher", he wrote in late March. In February, Capitol Police Chief Yogananda Pittman testified that even before the 9-11 attacks, security experts, including former chiefs of police, argued that more needed to be done to protect the Capitol complex. The attack underscored that the building and campus - and the officers charged with protecting them - remain potential targets for violence. Sections of surrounding roads have reopened for traffic.
Biden said that he knows what a hard time it's been for the Capitol and all who work there and protect it. Friday's incident came about three months after the January 6 insurrection that killed a Capitol police officer and four other people. "Officer Evans had been a member of the United States Capitol Police for 18 years".
Police identified the officer who died as William "Billy" Evans. Pelosi and Schumer both spoke Friday with members of Evans' family.
"We send our heartfelt condolences to Officer Evans' family, and everyone grieving his loss", President Joe Biden said in a statement. He ordered flags at the White House to be lowered to half-staff. Miriam Carey's family said she suffered from postpartum depression with psychosis but was not unsafe.
The crash and shooting happened at a security checkpoint near the Capitol typically used by senators and staff on weekdays, though most are away from the building during the current recess.
One officer has died of their injuries, another is in hospital in a "stable and non-threatening condition".
The U.S. Capitol Police said on Twitter that the incident occurred at an access point along Constitution Avenue. "It looks bad to have the beacon of our democracy surrounded by razor wire and National Guard troops".
Green's Facebook page, which has since been taken down, included photos and videos of Nation of Islam rallies, and the bio identified Green as a "Follower of Farrakhan".