US authorities are investigating car collisions involving US Secretary of Commerce John Bryson, who was later found unconscious at the wheel.
There were three collisions on Saturday near Los Angeles, California, after which Mr Bryson was treated for non-life-threatening injuries, police said.
They said there was no initial indication of alcohol or drug use and no charges have yet been filed.
Mr Bryson, an ex-Edison International chairman, took office last October.
A media release from San Gabriel police and the Los Angeles County Sheriff's Department said initial investigations showed the first crash was caused by Mr Bryson.
It said his Lexus struck a Buick that was waiting for a train to pass in the city of San Gabriel.
Mr Bryson spoke to the three male occupants then left the scene, apparently hitting the car again as he did so, the media release said.
The Buick then followed Mr Bryson's Lexus and the occupants called for police assistance.
Mr Bryson was then involved in a collision with a Honda a few minutes later as he crossed into the nearby city of Rosemead, where he was found alone and unconscious behind the wheel.
The law officials said the San Gabriel incident was being investigated as a felony hit and run.
There were no serious injuries to the passengers in the Buick and Honda.
Mr Bryson's Lexus and the Honda suffered minor damage, police said.
They said all parties involved had been co-operative.
LA County Sheriff's Deputy Mark Pope told local radio that authorities understood that Mr Bryson had a "pre-existing medical condition".
Mr Bryson helped develop Edison International into a leading solar and wind power firm, and was confirmed as commerce secretary despite some conservative objections to his pro-environmental connections.