Traffic was snarled for hours today on a busy Indiana highway after a double-decker bus traveling from Atlanta to Chicago flipped on its side, injuring dozens.

Authorities said that a little before 5 a.m. near Indianapolis, the bus-operated by Megabus-had attempted to avoid a stopped vehicle that had been in a previous crash on Interstate 65.

As the bus swerved, it overturned. Authorities said the bus was carrying about 60 people.

One passenger was reportedly hospitalized in critical condition but no life-threatening injuries were reported.

Bus passenger Craig Steichen of St. Charles, Illinois, said he was sleeping when the crash occurred. Steichen took cellphone video of emergency responders treating passengers.

"The scariest moment was … I guess when I was rolling around not knowing what was going to happen. … I don't know how many times it [the bus] rolled over but I know I moved about three or four different times," he told ABC station WLS-TV in Chicago.

Steichen suffered a skin burn on his forehead.

He said that it had rained the entire bus ride. State Police said weather likely played a role in the accident.

"The driver apparently didn't see it [the accident] because of the rain or something," State Police Sgt. Shawn O'Keefe told The Associated Press. "The bus driver swerved and ended up turning the bus over on its side, and it went into the median."

A second Megabus was sent from Louisville, Kentucky, to transport passengers to their final destination.

Megabus "will be providing assistance and support for all of our customers involved in this incident," said spokesman Sean Hughes. "Safety is our absolute priority and we are assisting the authorities with their investigation into the circumstances of the incident."