MANILA (AFP) - A Philippine military helicopter operating in the rebellion-torn southern Philippines crashed into a mountain on Saturday, killing three people, the air force said. The Bell UH-1H aircraft pitched into Mount Sinumaan on Jolo island when its crew attempted to land at a military outpost there, air force spokesman Lieutenant-Colonel Miguel Ernesto Okol said. The UH-1H attempted a precautionary landing... due to mechanical problems, he said in ad statement. He did not say what had caused the mechanical problem.