Five people died in the assault, including a US Capitol Police officer and one rioter who was shot by a USCP officer. An investigation has been opened.
Pittman said the suspect did not appear to have been on the police's radar.
In addition, two officers, one from Capitol Police and another from Washington's Metropolitan Police Department, died by suicide following the January 6 attack. "Please keep Officer Evans and his family in your thoughts and prayers".
Whether the extra fencing around the Capitol was needed after the deadly January 6 insurrection has been a point of controversy in Washington, D.C. And despite Greene's sign, the fencing is under the purview of U.S. Capitol Police, not Pelosi, and was erected by law enforcement and the military.
U.S. Capitol Police officers stand near a vehicle that crashed into a barrier on Capitol Hill in Washington, D.C., Friday.
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.
Flags will be flown at half-staff until sunset Tuesday.
Biden lays out 'once-in-a-generation' infrastructure plan
The plan includes some US$620 billion in transport, with Biden targeting a hike in the corporate tax rate to finance the spending. In doing so, it would expand the role of the government in the US economy to levels not seen in decades.
The attack comes as the Washington region remains on edge almost three months after a mob of armed insurrectionists stormed the Capitol as Congress was voting to certify Joe Biden's presidential win.
The U.S. Capitol complex was placed on lockdown after the shooting and staff were told they could not enter or exit buildings.
Congress is now on recess. A street sign visible on the right side of the picture indicates she was standing on Independence Avenue, which is on the south side of the Capitol building (opposite of where the April 2 incident occurred).
Capitol Hill has been tense over the past three months. One witness, the Rev. Patrick Mahoney, said he was finishing a Good Friday service nearby when he suddenly heard three shots ring out.
The officers struck by the auto were also taken to a hospital, where one of them, William "Billy" Evans, an 18-year department veteran, died from his injuries, officials said.
Shortly after 13:00 local time (18:00 GMT) the Capitol Police alert system sent an email to lawmakers and their staff ordering them to stay away from exterior windows and doors. Videos and photographs from the scene showed a blue vehicle rammed into a security barricade, a front door open. Chief Contee told reporters the suspect appeared to act alone.
The Washington, D.C. Metropolitan Police Department, which is taking over the investigation into what occurred, followed the announcement of the fallen officer's identity with its own condolences. The US Attorney General is also aware of the incident and is being updated, according to CBS News.