A 13-year-old boy from Massachusetts courageously took his 4-year-old sister to safety during an apparent murder-suicide in their house. The boy grabbed his sister and escaped the house through a window on Tuesday night while a man shot and killed his girlfriend and then fatally shot himself, police said in a press conference. “The 13-year-old is a pretty courageous young kid,” Worcester District Attorney Joseph Early said. “He took the 4-year-old in his arms, opened the window, ran out the window to a neighbor’s house.” Police said that the woman called 911 first but they couldn’t make out what was happening, then another call came in from the gunman himself. The neighbor that received the boy and his sister also called 911. The motivation for the tragic event is not clear yet, as the investigation is still in its early stages. There was another 3-year-old child in the house, who …