A partial roof collapse at a 30-unit apartment complex in Lawrence displaced several families Monday, officials said. Ashley Studley, a spokeswoman for the American Red Cross of Eastern Massachusetts, said that volunteers were called in the afternoon to the scene at 6 Inman St. and that a local school was being offered as a shelter for affected families. Police and fire officials could not be reached for comment late Monday. It was not immediately clear whether anyone had been injured or if the collapse was caused by heavy snow buildup.Travis Andersen can be reached at email@example.com. Follow him on Twitter @TAGlobe.