Updated at 10:09 p.m. ET
INDIANAPOLIS A bus carrying teens coming home from a church camp crashed Saturday after exiting an interstate in Indianapolis, killing three people and sending others to hospitals, officials said.
Indianapolis Fire Department spokeswoman Capt. Rita Burris confirmed to CBS News that three people died. Five people were trapped in the wreckage but were extricated within 20 minutes, Burris said. Some of the victims were taken from the scene by helicopter.
The bus came speeding off of Interstate 465 in northern Indianapolis, about a mile from the Colonial Hills Baptist Church that passengers attended and the bus' final destination. It struck a retaining wall as it tried to round a curve and overturned. The campers were returning from Camp CoBeAc in northern Michigan, about six hours away. The church's youth pastor had set a tweet a couple of hours before the crash saying the group was expected to arrive at about 4:15 p.m., around the time the accident happened.
"They were not that far from home. ... That only adds to the tragedy," Indianapolis Public Safety Director Troy Riggs said.
The dead included a man and his wife, Riggs said. Authorities did not provide information about the third victim.
Riggs visited the crash scene with Mayor Greg Ballard before heading to the church. Riggs said there was no indication that the driver had a medical emergency and called the accident "a great tragedy."
Ballard said investigators were taking measurements and examining the bus to determine the cause of the crash.
WTHR-TV reported the bus driver told witnesses his brakes failed. Indianapolis Fire Department Lt. Ato McTush said police and fire officials had not determined whether the church-owned bus had mechanical issues.
Duane Lloyd told WTHR that he heard a loud noise behind him as he was traveling near the intersection and saw the crash around 4:15 p.m.
"I heard a skid. I looked back. I see this bus in the air and people falling out of the bus," Lloyd said. "I could have gone my whole life without seeing that."
Karen Woodard, a member of Colonial Hills Baptist Church, cried as she stared at the wrecked bus surrounded by pillows, water bottles and clothing. She said the bus was returning from a youth camp in Michigan and some of the teens had their parents with them.
"It's so terrible. I can't believe it," she said.
Indianapolis Fire Department said crews had to free five people who were trapped inside after the crash. Several stopped to help before first responders could arrive, including one man who helped pull the driver out of the bus, the department said.
"People were stopping their cars. People were literally trying to lift the bus," Lloyd said. "You just try to do what you can do."
Fire officials said the bus was carrying about 40 passengers and that the injured included children and adults.
Nine teenagers were taken to IU Health Methodist Hospital, including one in critical condition. Ten others, including nine teenagers and a toddler, were in stable condition at Riley Hospital for Children, a spokeswoman for the hospitals said.
Many of the patients were suffering head, arm and leg injuries, fire officials said.
Roads near the scene were closed, and authorities were urging people to use caution in the area. A hazardous materials crew was cleaning up diesel fuel that spilled in the crash.
Outside the church, a yellow school bus with the church school's name was parked outside with piles of sleeping bags and suitcases nearby. Families hugged outside and talked quietly before going inside, where they met with Ballard and Riggs Saturday evening.
Ballard described the families as "remarkably positive" despite their sorrow.
"Some of the teenagers are hurting pretty bad and you can see that in their faces," he said.
Church member Jeff Leffew, 44, of Fishers, who had three daughters on the bus that crashed and a fourth on a second bus, said he was waiting to pick them up in the church parking lot when the second bus arrived. He said he knew immediately that something was wrong because the kids on the bus were screaming.
He went to the crash scene and found his three daughters with only bumps and bruises.
He called the crash scene "surreal."