'Pioneer Woman' Ree Drummond's Nephew in Critical Condition After Crash

'Pioneer Woman' Ree Drummond's nephew is hospitalized in critical condition after an accident at the family's Oklahoma ranch, where her relatives were battling a fire.

The Oklahoma Highway Patrol tells TMZ ... Ree's 21-year-old nephew, Caleb Drummond, was involved in a head-on collision Wednesday, and the force of the crash sent his body flying 70 feet away.

OHP says Caleb was driving a fire truck when he crashed head-on into another fire truck driven by Ree's husband, Ladd Drummond. When they collided there was low visibility due to high winds on a dirt road, and we're told Caleb was not wearing a seatbelt.

He's been transported to a Tulsa medical center, where he's in critical condition with head, arm and leg injuries as well as internal bleeding.