Aston Villa boss Steve Bruce has criticised Birmingham City's decision to give their supporters cardboard clappers ahead of Sunday's Second City derby at St Andrew's.
Blues supporters repeatedly threw the clappers at Villa players during the goalless draw, prompting others to begin launching plastic bottles and even coins, with Ahmed Elmohamady one of two players hit.
"Whoever made the ridiculous decision to have clappers here obviously doesn't know the Birmingham-Villa game as the Birmingham fans don't need a clapper. It is the last thing they need," Bruce, a former Birmingham manager, told reporters.
"But they have somehow used them as a weapon. In all seriousness someone could have been badly hurt. They were rolled up, elastic bands around them and they became like a rock.
"Thankfully no-one has been caught. But people could have been. Two of the players were hit with them so whoever made the ridiculous decision, I don't think they will do it again."
Villa remain sixth in the Championship table following the derby draw, while Birmingham sit 21st in the standings.