EE & COWORKER WERE CLOSING TEMPORARY FENCE GATE & SECURING IT W/SMOOTH WIRE ATTACHMENT OF WOODEN TREE BRANCH. EE WAS PULLING ON WOODEN TREE BRANCH TO SECURE IT TO WOODEN POST & HIS COWORKER WA S PUSHING & PULLING ON T-POST & FENCE GATE THAT ARE TIED TOGETHER. AFTER HIS COWORKER REMOVED HIS HAND FROM PULLING TO ASSIST EE IN SECURING TREE BRANCH ON WOODEN POST, THE GATE FENCE JERKED