HOUSTON (KTRK) -- Police are looking for a gunman suspected of robbing a Shell station.Police say around 7am, the man walked into the Shell station at Veterans Memorial at Beltway 8 and demanded cash.The owner followed the suspect outside the store and shot at the thief, but it's still unclear if he was hit."I drew upon my training and I did what I had to do to protect me and my co-worker," the clerk told Eyewitness News.Canine units were called in to help search for the man. He is still at large.