At least one person has been shot near the US Capitol building in Washington DC and the area has been locked down, emergency services have said.
Staff inside the building were sent a message telling them no entry or exit was allowed and they were warned to stay away from exterior windows and doors.
The message added: "If you are outside, seek cover."
It is not known what condition the person who was shot is in, and their identity has not been confirmed.
US Capitol Police said they were responding to reports someone rammed a vehicle into two of its officers.
They said a suspect is in custody.
Both officers are thought to be injured.
All three have been transported to the hospital.