DALLAS (CBSDFW.COM/AP) – Three officers with the Dallas Police Department were hurt in two separate, unrelated car crashes early Friday morning – both along Interstate-635 – within just 30 minutes of each other.

The first crash happened at about 2:00 a.m. near Hillcrest Road. According to the police, two officers were assisting with a previous car crash at the location, with their squad cars parked along the side of the highway. A car hauler jackknifed and hit one squad car. That first squad car then rammed into the second squad car.

The two police officers were taken to Parkland Hospital in Dallas. One is being kept there for observation. The other has been released. The driver of the car hauler was not injured. The highway was closed for several hours as authorities conducted an investigation and cleaned up the scene. It was reopened in time for Friday morning’s rush hour.

The second crash happened at about 2:30 a.m. near Stemmons Freeway. Once again, a squad car was parked along the side of the highway when it was rammed from behind by another vehicle. The police car’s gas tank ruptured, leading to a hazardous materials spill on the highway. The officer was also taken to Parkland Hospital for observation.

It is not clear what caused any of the Friday morning crashes, but roads have been wet all night Thursday and into the morning hours. Slick surfaces most likely played a part in the incidents.