A dumb man was detained Monday in Qinghai Province on suspicion of killing six people and injuring two others, local police said. The suspect, who was only identified as Yang, was a member of a deaf-mute theft gang that earned their life in Xining, capital of Qinghai, according to the Public Security Bureau of Xining. Yang had suffered frequent beatings and insultings in the gang, so he hacked a number of the gang members in revenge at about 7:20 a.m. Sunday when they were sleeping, according to an initial investigation. Six people died on the spot and two were injured. Police captured Yang early Monday morning after more than 20 hours of hunting. 