CHICAGO (AP) — Prosecutors say a man who fatally shot five co-workers at an Illinois warehouse apparently took the gun and ammunition into the plant when he arrived that morning.

The Kane County State’s Attorney’s office said in the report released Monday that it found law enforcement officers used justifiable force when they killed the gunman, Gary Martin, during a shootout at the Henry Pratt Co. building in Aurora on Feb. 15.

The report says Martin used profanity and opened fire after he was told he was being fired.

It says before the meeting, Martin walked “over to his workstation to retrieve something,” put on a hoodie and went into the bathroom.