A man died after he drove off an open end of the Southwest Spokane Street Swing Bridge just before 1 p.m. yesterday.

Witnesses said the man, who has not yet been identified, passed several westbound cars waiting at the warning gates for the bridge to reopen, accelerated around them, and crashed through a wooden arm and a metal barricade before plummeting about 100 feet to the ground below, police said. The silver Volkswagen Jetta landed on its top east of the waterway.

Seattle police said the man died on impact.

The hydraulic bridge, which also is referred to as the lower-level West Seattle Swing Bridge, pivots open over the Duwamish River and connects Harbor Island to West Seattle.

The opening had been a routine one to allow vessels through the waterway, police said.

Police said they are investigating possible reasons for the crash, including whether there was a medical reason for the car being driven off the bridge or a vehicle malfunction.

Police said that, though there was a baby seat in the car, no other people were in the car at the time.

The bridge reopened about 7:15 p.m. after repair work, said Liz Rankin, a spokeswoman for the Seattle Transportation Department. She said the car damaged a wooden barrier arm and a steel bar that acted as an additional barricade.

As a safety measure, a flagger will be stationed on the bridge until the steel bar can be repaired, Rankin said, which is likely to take a couple of days.

Staff reporter Nick Perry contributed to this story. Christine Clarridge: 206-464-8983 or cclarridge@seattletimes.com