！
Don't kill uninvolved people!
Literal
Unrelated person [object-を] kill-[negative-imperative-な]!
Notable for the writing 殺る (やる, 'to kill' in yakuza/slang register) instead of 殺す (ころす). 殺る is a 当て字 substitution — taking the やる reading (normally the general 'do') and applying the kanji 殺 ('kill') to give it a rough, murderous sting. Common in fiction, gangster movies, and manga. The negative imperative な is direct and forceful.