According to a witness, people started running down into the creek bed to help the officer.
After the crash, the driver of the Silverado ran from the scene and police are continuing to search for the suspect.
Residents helped rescue the officer before he was taken to Methodist Hospital for treatment.
The officer was taken to a nearby hospital, where he is in stable condition.
"I immediately got on the phone to call 911 and told them they needed to get some officers here because one of their comrades had been involved in a crash, and he's in that creek there - and I think it's very bad - and they needed to get here as soon as they can, quickly".
The impact sent the officer's vehicle airborne over an overpass and into a creek 30 feet below, KXAS-TV (NBC5) reports. "And they were here quickly", Jefferson said.
Detectives want to know if the driver of the pick up truck intentionally hit the officer or simply ran the stop sign.
Dallas police are praising a group of people who helped a critically injured officer by scrambling down into a creek bed and stabilizing the officer's patrol auto after it was forced off the road by another vehicle.
Good Samaritans rushed to help a Dallas police officer after a serious crash. And I wouldn't have thought twice.
"They had just broken into and broke out my windshield and tore up the inside of my neighbor's auto". "And everybody was on the same page", Benji Rogers told NBC 5 in Dallas. "The love from our community is truly inspiring".