(CNN) -- Investigators probably will have to use dental records to identify some of the eight people who were killed in a wreck involving a church bus and two other vehicles in eastern Tennessee, a Tennessee Highway Patrol official said Thursday.
Some of the bodies in Wednesday's crash were burned or otherwise made unrecognizable, hindering authorities' ability to notify all of the victims' families about the deaths, highway patrol Sgt. Bill Miller said.
"The crash is so horrific ... it's probably the worst that I have seen in my career ... and I've worked in several, several counties in my" 17 years on the job, Miller said.
The bus, owned by a North Carolina church, was carrying a group of seniors on their way back home from a religious conference when one of its tires malfunctioned, sending the bus across a median on Interstate 40 and crashing into an SUV and a tractor-trailer, authorities said.
Eight people were killed: Six on the eastbound bus; one of three occupants of the SUV, and the tractor-trailer driver, the Tennessee Highway Patrol said.
Two of the 14 other people who were hospitalized after the wreck had been released by Thursday morning, said Travis Brickey, a representative of the University of Tennessee Medical Center.
Two people were in critical condition; seven were in serious condition, and three were in stable condition, Brickey said. None of the victims' names was released.
The church group -- about 18 people including the driver, Miller said -- was returning to the Front Street Baptist Church in Statesville, North Carolina, after attending the 17th annual Fall Jubilee conference in Gatlinburg.
The group of senior citizens was called "Young at Heart," said Rick Cruz, the church's pastor.
Twelve of the hospitalized victims -- including the two in critical condition -- are church members, Cruz said Thursday morning.
"It's been a very long night for all of us here," Cruz told reporters. "We are thankful for all the prayers and support that we've been receiving."
The wreck happened about 2 p.m. Wednesday in Jefferson County, about 40 miles east of Knoxville, the Tennessee Department of Safety said.
Miller said it wasn't clear exactly what happened to the bus tire, other than it malfunctioned or failed in some way.
The bus swerved across a grassy median and struck the SUV before hitting the tractor-trailer, he said. The bus came to rest on its side, pinning some of its occupants, he said.
Video from the site showed smoke rising from the tractor-trailer. Some people walked out of the bus on their own, but emergency personnel had to extricate others, Miller said.
"This was such a horrific crash that determining if seat belts were used or not ... may be extremely difficult to impossible to determine," he said.
Miller said it's too early to know whether charges will be filed in connection with the wreck.
CNN's Andrew Spencer and Rich Phillips contributed to this report.