EMPLOYEE WAS WORKING ON A DUCT CHUTE PATCHING HOLES. HE PLACED HIS PINCH BAR UP NEXT TO A DIVERTER GATE. AFTER WORK WAS COMPLETED, HE GRABBED THE PINCH BAR, WHEN HE DID THIS THE GATE SLAMMED SHUT PINCHING HIS FINGER BETWEEN THE BAR & THE DUCT. THEY WERE NOT WORKING ON THE GATE, HE JUST SET HIS TOOL NEXT TO THE GATE.