Officers were dispatched to the 9400 block of Cullen for a trespassing call just before midnight.
Officers say they were conducting an investigation when a man purposely hit their witness with a vehicle, and then hit the officer's patrol car.
The officer told Eyewitness News that he feared for his life, and took off on foot as the man sped towards him in his vehicle.
The officer fired several shots at the man, striking him multiple times.
The suspect was transported to the hospital where he is undergoing surgery.
Police say the witness was also transported to the hospital with a broken leg.