Four people were killed and nine others injured when a passenger van crashed in Wise County on Wednesday morning.

The crash occurred on U.S. Highway 287 near the  F.M. 1655 exit in Alvord, about 50 miles northwest of Fort Worth, at about 8 a.m.

“Preliminary investigation indicates the vehicle left the roadway, the driver overcorrected, causing it to lose control, which caused the vehicle to roll over multiple times,” Texas Department of Public Safety (DPS) spokesperson Tony De La Cerda said, per NBC5 DFW.

The driver and two other passengers were pronounced dead at the scene of the single-vehicle crash, and a fourth person died at a local hospital. Nine other occupants of the vehicle were transported to area hospitals for treatment of their injuries, with two of them reported to have sustained critical injuries.

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Only one of the vehicle’s 14 occupants was wearing a seatbelt, and that person reportedly walked away from the crash uninjured.

“Seat belts save lives. We emphasize that every holiday, every weekend, every day. Wearing your seat belt is going to save your life,” said De La Cerda, per NBC5. “In this case, only one person was wearing their seat belt and was able to walk away and was transported for precautionary measures.”

All occupants of the van were adults. The names of the dead and injured have not been released pending notification of next-of-kin.

The group of travelers had departed from Florida and were northbound on U.S. Highway 287 when the crash occurred, but their intended destination is unclear, ABC News reported.

The crash, reported as a “mass casualty event,” precipitated a large emergency response from local police, Texas DPS, and local fire departments and included several ambulances and medical helicopters.

The northbound lanes of traffic were shut down for several hours as DPS investigated the crash scene. The roadway was reopened to traffic on Wednesday afternoon.