WASHINGTON (AP) — The White House said Tuesday there was no timetable for Commerce Secretary John Bryson's return from medical leave, as California officials indicated the Cabinet member may not face criminal charges if a blood test shows no sign of drugs or alcohol.

President Barack Obama spoke with Bryson briefly Tuesday morning, their first conversation since the secretary suffered a seizure connected to two traffic accidents Saturday.

"The president encouraged Secretary Bryson to focus his thoughts on his own health and on his own family," White House spokesman Josh Earnest said.

Investigators are awaiting a blood test to determine if Bryson was under the influence while driving in the Los Angeles area. A Breathalyzer test administered to Bryson shortly after the crashes didn't detect any alcohol, authorities said.

The test results could come back as early as Wednesday.

"If it comes back clean, it's highly unlikely there will be criminal implications," said Steve Whitmore, a spokesman with the Los Angeles County Sheriff's Department.

Bryson, a 68-year-old former utility executive, informed the White House Monday that he was taking a medical leave of absence to undergo tests. He did not specify how long he would remain on leave but said he would not perform the functions and duties of the office "during the period of my illness."

As secretary, Bryson is a member of the president's economic team and has advised on energy issues. Deputy Secretary Rebecca Blank was named acting head of the Commerce Department in Bryson's absence, and the White House said she had the president's confidence.

Authorities said Bryson was driving alone in a Lexus in San Gabriel, a community of about 40,000 northeast of Los Angeles, when he struck the rear of a vehicle that had stopped for a passing train, authorities said. He spoke briefly with the three occupants and then hit their car again as he departed, investigators said. They followed him while calling police.

Bryson was cited for felony hit-and-run, although he has not been charged. The secretary then struck a second car in the nearby city of Rosemead, where he was found unconscious in his car, authorities said. Government officials said Monday he had had a seizure.

Bryson had not suffered a seizure previously, according to a Commerce Department official who spoke on condition of anonymity to discuss the secretary's medical history. It was not clear whether the medical episode preceded or followed the collisions. Bryson has a "limited recall of the events," the official said.

Bryson returned to Washington after a brief hospital stay, department spokeswoman Jennifer Friedman said.

Bryson was not on government business, was driving a personal car and did not have a security detail at the time.

The secretary had been in California to deliver the commencement address Thursday at Pasadena Polytechnic School, which his four children attended. The K-12 school said he urged students to pursue their passions, to serve their country and to value their education and friendships.

Some students and parents who saw Bryson's commencement speech told the Los Angeles Times he stumbled over some words, mispronounced others and appeared to lose his place several times.

The episode is consistent with someone who has suffered a series of epileptic seizures, said Dr. Jerome Engel Jr., a neurologist at the University of California, Los Angeles, who is not involved in Bryson's care.

After a seizure, a person is often confused, and that state of confusion can last for a while.

"You may even seem to be alert and awake, but you're not really behaving normally," Engel said.