(CBS News) INDIANAPOLIS - Investigators are trying to figure out if mechanical problems caused a bus returning from a church camp to crash. Three people were killed and dozens injured.
The bus was just a mile from its destination when it veered out of control near Interstate 465 in Indianapolis.
Colonial Hills Baptist Church is struggling with the loss of their youth pastor, Chad Phelps, and his pregnant wife, Courtney. Tonya Weindorf, a mother of five, was also killed.
Indianapolis police are investigating. The driver told them his brakes failed as the bus was exiting the highway.
One bystander told CBS News: "It was going very fast. I have no idea how fast but the light had turned green for the southbound through traffic and then the bus just flew into my vision right away and flipped, just, in an instant."
Bystanders quickly moved to help the dozens of injured passengers.
"I saw a lot of back injuries, a lot of contusions, a lot of head and neck injuries," said Dr. Azam Ghafoor.
Another bystander told CBS News: "I think the driver was the first one I came up on and he was bleeding pretty bad, so I stole somebody's belt, from the best that I can remember, and got a tourniquet on his arm."
No criminal charges have been filed. Eleven victims remain hospitalized.
The Phelps' two year old son survived the crash.