Police say a southbound truck was attempting to make a left turn in the 22100 block of Highway 99 when a van coming in the opposite direction veered into the center lane and crashed head on into it.
The man behind the wheel of the van -- which turned out to be stolen out of Lynnwood -- bailed out after the crash and tried to make his getaway on foot, police say.
Several people who saw the crash gave chase, catching the man near Edmonds Furniture. They held him down until police arrived.
The 48-year-old man who was driving the truck was taken to Harborview Medical Center, as was the 68-year-old woman who was riding with him. The extent of their injuries is unclear.
The man who caused the crash, who has not been identified, was taken to Swedish Hospital in Edmonds to be treated for his injuries. When he's released, police will book him into Snohomish County Jail on suspicion of hit-and-run with injuries and possession of stolen property.
Police temporarily shut down a portion of the highway while they cleared the scene and investigated the crash.