Something happened to him — hurry to the hospital!
Tips
usage
出事 always has a negative connotation. It can refer to traffic accidents, workplace incidents, or any unfortunate event. You'd never use it for something positive.
grammar
出事 is a verb-object compound. You cannot insert 了 between them — say 出事了, not 出了事 (though 出了事故 is fine with the full word 事故).
