Authorities say a church van returning from a youth outing overturned on an interstate off-ramp in Tennessee, killing a teenage girl and injuring several others.

Sgt. Chad Smith of the Tennessee Highway Patrol said there were 12 people in the van when it crashed Thursday morning about 55 miles west of Nashville. Troopers say several youths had been returning from a so-called lock-in at a church in Memphis.

Children and teens typically stay up all night to participate in "lock-in" activities, and troopers say they are investigating the possibility that the driver fell asleep.

Trooper Bruce Gildersleeve says 14-year-old MacKenzie Turner was killed in the wreck.

Ashley Culver, who is a spokeswoman for Vanderbilt Children's Hospital in Nashville, says three children taken there had been upgraded to stable condition.