A Texas Department of Public Safety trooper was injured in a fatal vehicle collision in northern Fannin County Monday as she responded to a separate deadly crash.

DPS Staff Sgt. Mark Tackett said the initial collision, which prompted a response from troopers, occurred shortly before 10:45 a.m. on State Highway 78, near the intersection of that roadway with FM 1396. Tackett said Bobbie Dunn, 35, of Bonham, attempted to make a U-turn across the highway from the shoulder and was struck by a semi-trailer. Dunn was pronounced dead at the scene and the driver of the semi-trailer was not injured.

Tackett said the unnamed trooper was traveling toward the wreck via State Highway 121, when an oncoming vehicle turned in front of her patrol car.

“The trooper was northbound and had lights and sirens activated,” Tackett said. “Eighty-year-old Robert Moncelle was southbound and he turned in front of the patrol unit and they collided at the intersection.”

Tackett said the trooper broke her leg in the crash and was transported to Texoma Medical Center before she was eventually flown to a Dallas-area hospital for surgery. Moncelle, also a Bonham resident, was taken to an area hospital where he died several hours later.

The collision involving the trooper remains under investigtion.