1. To kill thoughtlessly or without concern and an undisciplined way; to slaughter.
2. Informally, to defeat decisively or handle something badly: "Andrew massacred the German language as he tried to explain what happened."

A reference to having killed a large number of people; especially, people who were not involved in any fighting or have no way of defending themselves: "The stories of the massacred people in Syria have been in the news for too long!"