Chris Karnes, who was on anon an overpass in Washington state on Monday, described how the incident unfolded -- and what it was like for passengers on the train.
"We had just passed the city of DuPont and it seemed like we were going around a curve," Karnes told CBSN. "And all of a sudden, we felt this rocking and creaking noise, and then all of a sudden it felt like we were heading down a hill, and the next thing that we know, we're being slammed into the front of our seats, and the windows are breaking, and then we stop, and there's water that's gushing out of the top of the train, and all the lights go out and people are screaming."
"There was a lot of dust all over the place, and in order to get out of the car we had to kick out the window, the emergency window, because the emergency doors were not functioning," Karnes, who says he was near the front of the train, later told CBS News in a special report.
"There was a little bit of creaking initially but there wasn't a whole lot of warning," he added.
He said he saw people with cuts and bleeding, as well as one person on the ground who was not moving.
Authorities say "multiple fatalities" and injuries have been reported.