Israeli troops on Friday shot dead three heavily armed gunmen who sneaked across the Egyptian border and ambushed troops, averting "a very big terror attack," a military spokesperson said. "They opened fire toward IDF [Israel Defence Force] troops that were guarding the workers [building the fence] in that area. Another force that was nearby ... rushed to the area and targeted those three terrorists," said spokesperson Lieutenant Colonel Avital Leibovich, saying all three were killed.