Come on In, We're Dead (2017)

The true story of the deadliest shootout for lawmen in US history, 10 cops and one civilian went to arrest 2 brothers for murder on Jan 2, 1932, just outside Springfield Missouri. The Sheriff had been neighbors with the brothers family and didn't expect any trouble, they were wrong, of the 10 lawmen and one civilian, 9 were shot and 6 killed, it stands as the deadliest shootout for cops to date.