A Trinity Railway Express train struck a pickup truck in Irving on Thursday afternoon, killing the driver.
Dallas Area Rapid Transit spokesman Morgan Lyons said the collision occurred just before 1 p.m. at the Irby Lane crossing near Rock Island Road.
Lyons said a red truck was traveling east on Rock Island Road and turned north onto Irby Lane and into the train crossing as the eastbound train approached.
The train and the crossing signals both appear to be operating properly, Lyons said.
Witnesses told NBC 5 that the safety arms appeared to be malfunctioning and were up right before the crash. But a safety mechanism triggered by another vehicle had caused the arms to go up, Lyons said.
Video of the crash shows that all four arms were down before the train entered the crossing, Lyons said. But another vehicle -- a white truck traveling southbound -- made contact with the northwestern-most arm, which activated a safety feature that raised the southernmost-arm, he said.
"The system thinks the white truck is on the tracks and is making it possible for the truck to get off," he said. "That's why the southwest arm -- the one the white truck would use if it was trying to get out of the crossing -- was up. The system also raised the northeast-most arm. That would be the escape area for a vehicle traveling north."
The truck that was hit, a red pickup truck, then entered the crossing going north on Irby Lane in the southbound lane, Lyons said.
"That arm is up and coming back down," he said. "The red truck then makes a sharp turn to enter the northbound lane. That crossing arm is coming down after being activated by the action of the white truck. The red truck is hit in the crossing as it tries to go north after entering from the southbound lane."
Lyons said the train crossing is in a quiet zone, meaning trains aren't allowed to blow their horns to warn drivers. Safety arms, flashing lights and bells are the only warning for drivers, he said.
The crash is under investigation, DART said.
None of the approximately 80 passengers and crew on the train were injured, DART said.
DART provided shuttle buses in the area to help train passengers get to their destinations while the accident scene was cleared. TRE resumed normal operations shortly after 3:30 p.m.
NBC 5's Omar Villafranca contributed to this report.