"White House staff are in touch with law enforcement and monitoring the incident," said a White House official.
"Questions about the security posture at the White House complex should be directed to the United States Secret Service," the official added.
Witnesses reported hearing gunshots outside the west side of the Capitol about 2 p.m. Thursday.
Law enforcement officials rushed to the scene as lawmakers and staff took cover, and locked down the complex.
Police lifted the lockdown at 3 p.m.
Unconfirmed reports said that the incident began when a car attempted to ram the White House barricade, leading to a chase which ended when the suspect was shot by officers. A Capitol Police officer was injured in the incident.
This story was published at 3:17 p.m. and has been updated.