A 6-year-old girl was killed, and three other children were taken to local hospitals, along with an adult, after a wreck just outside of Stilwell, the Oklahoma Highway Patrol reported.Open the video player above to see some of the headlines KOCO 5 is following.About 1:10 p.m. Thursday, Kelsey Vann, 28, of Stilwell, was driving along OK-51, about three miles west of Stilwell, when the single-vehicle collision occurred. The cause of the wreck remains under investigation, troopers reported.Vann was flown to a Tulsa hospital in critical condition. The 6-year-old girl, a passenger in the vehicle, died at the scene. Three other children, ages 2, 7 and 12, were taken to local hospitals to be treated for their injuries, OHP reported.>> Download the KOCO 5 AppTroopers said seatbelts were equipped in the vehicle but were not in use by four of the occupants. A 2-year-old girl was in a child restraint.No other information about the collision was released.Top HeadlinesSuspect tied to multiple Oklahoma murders captured in Arkansas after multi-day manhuntDriver arrested after leading police on high-speed chase in stolen carWoman who worked as a 'Rosie the Riveter' during World War II celebrates 100th birthdayMan accused of sexual abuse could have victims in OklahomaGrady County deputies find $100K of stolen agricultural equipment thanks to concerned citizen