SEATTLE – A semi-truck hauling fish overturned on State Route 99 near the Alaskan Way Viaduct Tuesday afternoon. Blocking all southbound lanes for nine hours. The lanes were re-opened just before midnight.

The accident happened near Atlantic Street, just south of the viaduct.

Traffic on the viaduct was at a standstill and the gridlock extended through the streets of downtown Seattle. Entire busloads of people stuck on the viaduct decided to disembark and walk off the viaduct.

Traffic flow was reversed so drivers could exit off the viaduct off the Columbia Street on-ramp. Motorists were also on exiting Highway 99 at Denny Way, just north of the Battery Street Tunnel.

At one point, city transportation officials said a cross-town trip from Elliott Bay to Interstate 5 -- a distance of a little more than a mile -- took an hour.

The Seattle Department of Transportation said the contents of the trailer had shifted after the rollover, making it unstable to transport. The trailer was to detached truck to pull it off the roadway.

The truck driver was taken to Harborview Medical Center with non-life-threatening injuries. Police are investigating the accident.