A gunman killed one person and injured several others in an attack inside a lecture hall at Germany’s oldest university in Heidelberg on Monday, security sources told dpa. Police said earlier that the perpetrator, who used a long-barrelled firearm, was dead and is believed to have acted alone. “We assume that there was only one perpetrator. At this stage we see no further danger to the public,” police said over an hour after the first reports of an attack emerged. Sources told dpa that the gunman was a student. After he entered the lecture hall and fired at the people gathered there, he left t…