The phrase "massive casualty" refers to a situation where a large number of people have been injured or killed, usually as a result of a disaster, accident, or war. Full definition
18 - wheeler truck accidents, buses and other commercial vehicles can cause massive casualty as a result of the sheer size of the vehicles involved. (dlalaw.com)
Bus accidents and 18 - wheeler accidents specifically can result in massive casualty due to the sheer size of the commercial vehicles involved in the crash. (dlalaw.com)
In my view, the Chinese would not be terribly upset to see the US dragged into a war that would weaken Washington if it lost and would cause massive casualties on all sides if it won. (businessinsider.com)