Forum:Gun Shop Help Needed

Ok, I just unlocked the gun shop from completing the misssion called 'Do You Have Protection?' and I decided to kill the guy who sells the guns hoping that I could steal lots of guns... I got a gun from him with a few bullets in it but that was it. Now whenever I go in his shop he starts shooting at me. Is there a way I can regain his trust and start buying guns again or am I stuck gun shopless forever?