Washington (CNN) -- U.S. Secretary of Commerce John Bryson, under investigation for possible felony hit-and-run after allegedly causing two weekend car accidents in California, will take a medical leave of absence "as he undergoes tests and evaluations," White House Press Secretary Jay Carney said Monday night.
A Commerce Department spokeswoman said earlier Monday that Bryson, 68, had suffered a seizure when the two accidents occurred Saturday.
Police said Bryson was found unconscious at the wheel of his car on after the two accidents.
Bryson was issued a citation at an area hospital where he received treatment, said Lt. Ariel Duran of the San Gabriel Police Department. Authorities must still decide whether to formally file any charges.
Bryson voluntarily took a breathalyzer test that detected no alcohol use, the Los Angeles Sheriff's Department confirmed Monday. Results from a separate blood alcohol test were pending, Duran said.
A police statement Sunday said the investigation was in "its preliminary stages," and that there was no indication of alcohol or drugs playing a role.
"Secretary Bryson was involved in a traffic accident in Los Angeles over the weekend," said a statement by Commerce Director of Public Affairs Jennifer Friedman. "He suffered a seizure. He was taken to the hospital for examination and remained overnight for observation. He was released and has returned to Washington. The investigation is ongoing."
At the White House earlier Monday, Carney said Bryson has "health-related issues that played a role" in the weekend incident.
Carney provided no further details, noting the Commerce Department statement about Bryson suffering a seizure.
"He was alone, he had a seizure, he was involved in" the accidents, Carney said in explaining the difficulty in determining exactly what happened.
In announcing Bryson's medical leave of absence Monday night, Carney said in a statement that Bryson had notified the White House of the leave and, "The President's thoughts are with Secretary Bryson and his family during this time."
Neither Carney's statement nor his remarks earlier indicated whether Obama had spoken directly with Bryson since the accidents.
According to a Commerce official, Bryson was on personal time with no security detail when the accidents occurred and was driving his own vehicle. The official, who spoke to CNN on condition of not being identified, said Bryson was given medication to treat the seizure.
The Commerce official said Bryson flew back to Washington on Sunday night and was in the office Monday. Bryson, who never had a seizure before, is in touch with doctors who are monitoring his progress, the source said.
Bryson has limited recall and the cause of the seizure, as well as the exact sequence of events, is not clear, the official said.
An administration official, also speaking on condition of not being identified, told CNN the White House was notified Sunday night about what happened.
Bryson, who was driving a Lexus, rear-ended a Buick occupied by three men that was stopped at a railroad crossing in San Gabriel, said the police statement Sunday.
"Bryson spoke with the males, then left the scene, hitting the same car again as he left," the statement said.
The men in the Buick followed Bryson while calling 911 to report the accident, it said.
Bryson then drove to the neighboring city of Rosemead, where he hit a second car, according to authorities.
The commerce secretary was found "alone and unconscious behind the wheel of his vehicle," according to the police statement.
Paramedics treated him at the scene and took him to an area hospital, Duran said.
Two of the three men in the Buick were treated for minor injuries, according to police.
Bryson was cooperative with deputies when he "came to," said Los Angeles County Sheriff's Department spokesman Steve Whitmore.
"It's all under investigation, and it will be treated as we would treat any investigation such as this," he said.
Obama nominated Bryson to succeed Gary Locke as commerce secretary in May 2011.
"As Commerce Secretary, John is going to be an important part of my economic team, promoting American business and American products across the globe," Obama said then. "By working with companies here at home, and representing America's interests abroad, I'm confident that he's going to help us meet the goal that I set of doubling our nation's exports."
Bryson's Senate confirmation was delayed by Republican opposition. It eventually occurred in October and he became the 37th secretary of commerce.
A graduate of Stanford University and Yale Law School, Bryson served as chairman of the California utility company Edison International from 1990 until 2008.
Before that, he was a co-founder of the Natural Resources Defense Council, a leading environmental group that strongly endorsed Bryson's nomination last year.
CNN's Tom Cohen contributed to this report.