US commerce secretary John Bryson is facing felony hit-and-run charges following two Los Angeles-area traffic crashes that left him injured and unconscious, police said.
The US Commerce Department said Mr Bryson suffered a seizure in connection with the accidents and has returned to Washington after being released from a hospital.
Mr Bryson, 68, was treated following the crashes on Saturday evening, the Los Angeles County Sheriff's department and the San Gabriel Police Department said. He is facing felony hit-and-run charges, a police spokesman added.
The commerce secretary was driving alone in a Lexus on a main street in San Gabriel when he allegedly struck the rear end of a vehicle that had stopped for a passing train.
He spoke briefly with the occupants and hit their car again as he departed, officials said. The car's occupants followed him while calling police.
Mr Bryson then allegedly struck a nearby car minutes later. He was found alone and unconscious in his car and was treated at the scene before being taken to a hospital.
There was no immediate indication that alcohol or drugs played a role, the departments said. Authorities do not know if Mr Bryson had a prior medical condition.
"When the first officer rolled up on the scene, he was behind his wheel unconscious," the police spokesman said. "But our officer did speak with him at the hospital."
Two people in the first collision were treated by paramedics after complaining of pain, according to officials. The couple involved in the second crash also complained of pain but declined medical aid. Damage to the vehicles was minor.
As commerce secretary, Mr Bryson has played a role as a member of President Barack Obama's economic team and has worked to promote job creation. Mr Obama swore in the former utility executive to head the US Commerce Department in October, after he easily overcame conservatives' objections that his pro-environmental views made him unsuited for the job.