State troopers are investigating a man on suspicion of vehicular assault after a rear-end crash on I-405 Saturday that sent a woman driver in another car and her passenger to the hospital.

It happened around 3:20 p.m. on the northbound lanes, near Highway 527.

Troopers said the man, 20, was driving a Mercedes SUV when he ran into the back of a Lexus SUV that the woman was driving. The Lexus went into a ditch and rolled over. The Mercedes wound up on the right shoulder.

Investigators from the State Patrol suspect that the Mercedes driver was intoxicated, trooper Heather Axtman said. He was booked into the Snohomish County Jail. Neither he nor the woman riding with him were injured.

The Lexus driver, who is in her 50s, was listed in satisfactory condition Sunday at Harborview Medical Center in Seattle, a nursing supervisor said. Her passenger, a man in his 20s, was discharged from the same hospital Saturday night.