HOUSTON -- The Houston Police Department said it is investigating an early-morning wreck in southeast Houston that sent one of its officers to an area hospital.

Authorities said Officer Lloyd Morrison stopped to investigate a wreck at about 3 a.m. at 45th and Cullen streets along with a fire crew, when one of the vehicles involved in the crash slammed into his patrol car.

Investigators said Morrison then exited his car and was checking on the people in the vehicle when another car ran into his patrol car, pinning him between the vehicle and a fire truck.

The fire department was able to pull him from between his vehicle and the fire truck by lifting his car off of him, police said.

Morrison and the drivers from each car were transported to Ben Taub Hospital. Morrison is currently listed in critical but stable condition following surgery.

There is no word on the condition of the drivers.

Police the two drivers are accused of drunken driving and are expected to be charged with DWI when they are released from the hospital.