OKMULGEE COUNTY, Oklahoma - A 6-year-old girl is dead after a crash at Highway 16 and Highway 75 in Okmulgee County. 

OHP said six people were in a minivan that had been heading north on 75 and was exiting the highway. The van collided on the off ramp with a pickup going  eastbound on Highway 16.

Troopers say also in the van were two adults, driver Cynthia Watkins, 25, and 32-year-old Cody Watkins, and three other children from 13 months to 6 years, all girls. The other 6-year-old girl was flown to the hospital in critical condition.

Everyone in the pickup - four teenage boys from Beggs and Mounds - refused treatment, a collision report states.

The cause of the crash and who is at fault is still still under investigation. Troopers say they're also investigating seat belt use.