4 dead, 12 in critical condition after amphibious tour vehicle collides with bus on Seattle bridge

As many as 12 people were critically injured, and there were reports that four people are dead after an amphibious vehicle collided with a charter bus on a bridge in Seattle.

90 firefighters responded to what Seattle Mayor Ed Murray calls a terrible tragedy.

The crash was reported late Thursday moing on a bridge over Lake Union. Harborview Medical Center spokeswoman Susan Gregg said the hospital expected to treat up to 10 of the most seriously injured victims, while as many as 15 others were being taken to other hospitals in the area.

A witness said she was walking across a Seattle bridge just after the bus and the "duck boat" crashed and she said came upon a mess of jumbled metal and glass.

Jahna Dyer, a registered nurse, told The Associated Press on Thursday that some victims were sprawled out on the pavement while others milled about seemingly in shock and falling down.

The Seattle Fire Department said about 50 people were evaluated and that all victims have been removed from the wreckage.

A triage center was set up on the Aurora Bridge. Video from KIRO-TV shows firefighters extricating riders from the amphibious vehicle.

The amphibious, military-style tour vehicles are operated by a tour company called Ride the Ducks and are known for exuberant drivers and tour guides who play loud music and quack through megaphones as they lead tourists around Seattle, The Associated Press reported.

In 2010, a barge plowed into an amphibious vessel packed with tourists that had stalled in the Delaware River in Philadelphia.

STAY AWAY from #Seattle Aurora Bridge. Bridge will be closed for a long time. LIVE: http://t.co/pvFp8s386Gpic.twitter.com/gEkWCu6rJX — Morgan Palmer (@MorganKIRO7) September 24, 2015

The wreckage is blocking all northbound and southbound lanes.