The clerk, who is the son of the owner of the store, returned fire. That clerk and one of the suspected robbers were both hit.
One of the suspects and a female he was with left the scene, leaving behind the car they were in.
"He fled on foot northbound on Veteran's Memorial," said Sgt. L.A. David with the Harris County Sheriff's Department. "We have the suspect vehicle here on the scene which will be processed as evidence."
The clerk is listed as stable, while the suspect is in serious condition.
Investigators are hoping to develop a description of the man and woman who took off from the store security camera video. If you have any information in this case, you're asked to call the Harris County Sheriffs Office.