The Los Angeles district attorney's office announced Tuesday it will not charge former U.S. Commerce Secretary John Bryson over a string of car crashes last month.

The office declined to prosecute the case after San Gabriel police reportedly sought felony hit-and-run charges against the ex-official.

But in a document released Tuesday, the district attorney's office said doctors believed Bryson's claim that he had suffered a seizure.

"Both treating doctors agree that suspect was suffering from confusion following a seizure and crashed as a result," the document said. It said Bryson tested positive for a "low" level of Ambien -- but that it could not be cited as a factor in the crashes and that Bryson also tested negative for alcohol and controlled substances.

Bryson resigned June 21 after the incident. He claimed he suffered a seizure and that he didn't want his health to be a distraction from his job.

Authorities said Bryson struck a car stopped for a train twice and then rammed into another vehicle with his car a few minutes later. He was found unconscious in his vehicle.

The Los Angeles County Sheriff's Department and the San Gabriel Police Department said that in the first crash, Bryson was driving alone in his Lexus on a major street when he allegedly struck the rear end of a Buick. He spoke with the occupants of that car before leaving the scene and "hitting the same car again as he left the scene," according to a police statement.

The agencies said minutes later he struck another vehicle, a Honda Accord, in a nearby community, and police found him unconscious behind the wheel of his car. Bryson took a brief medical leave of absence from the Obama administration before resigning.

The Associated Press contributed to this report.