HOUSTON, Texas (KTRK) -- Police are looking for two men they say killed an innocent bystander during a robbery Sunday morning.According to police, two men attempted to rob a convenience store on Bissonnet and Fondren just before 4 a.m. The store also has a payday advance business associated with it.Police say the clerk tried to fight back when the suspects got to the cash register and a homeless man attempted to help. During the struggle, the man was shot in the chest and killed.Police previously believed the man who was killed was an employee of the store.The suspects are on the run. Police described them as Hispanic males in their late teens or early 20s.