Compeán said he thought the suspect had a gun and was going to shoot him so he fired at him first. His shot missed but his partner, hearing gunfire, fired in order to defend Compeán and hit the suspect in the buttocks.
Compeán assumed the suspect was armed and would shoot him, leading him to fire first. His shot missed but his partner, alerted by the shots, fired back to protect Compeán and hit the suspect in the buttocks.