The White House is on lockdown after a vehicle struck a security barrier.
The US Secret Service tweeted that the vehicle "did not breach the security barrier of the White House complex."
No shots were fired during the incident, the Secret Service said.
The agency added that the female driver of the vehicle was "immediately apprehended."
Witnesses saw a commotion on the White House grounds as security officers responded.
President Donald Trump is hosting Australian Prime Minister Malcolm Turnbull at the White House.
Turnbull is remaining at the White House as the incident is being investigated.
The Secret Service says no law enforcement personnel were injured in the incident.