A police department spokesperson said one of the 57 people injured appeared to be in critical condition.
"People were thrown into the air and onto the ground," passenger Elizabeth Banta told CNN. "There were definitely many people on the ground who were not moving."
More top news
Tonight a band of cloud and rain will spread into Scotland and Northern Ireland.
Greenpeace has obtained leaked documents which reveal how much the US has been pushing the EU on the TTIP trade agreement.
Appeals court clears the way for case against U.S. Army Sergeant and former Taliban prisoner Bowe Bergdahl to resume.