DALLAS (CBSDFW.COM) – A crash that happened just before midnight shutdown part of the Dallas North Tollway in Plano.

A spokesman with the Texas Department of Public Safety (DPS) says what ultimately was a 4-vehicle crash is believed to have started with a Mustang traveling north on the Tollway. Investigators believe the driver – for some unknown reason – ran into a BMW traveling in the same direction.

The collision sent the Mustang spinning and it smashed into two other vehicles.

(credit: CBSDFW.COM)

The driver and a passenger in the BMW were taken to Texas Health Presbyterian Hospital in Plano with serious injuries. There were no serious injuries in the other vehicles involved in the crash.

The driver of the Mustang was arrested on suspicion of Driving While Intoxicated.

Traffic is being forced off the Tollway at Parker Road while the investigation into the accident continues.