MARAWI CITY, Philippines - Philippine armed forces helicopters fired guided rockets at Islamist militant positions on Saturday in an attempt to end a siege in the southern city of Marawi that has raged for five days.The use for the first time of the heavy firepower came amid growing confidence that the location of the man believed to be the leader of the Islamic State-inspired fighters, Isnilon Hapilon, has been pinpointed in the city."We are trying to use our maximum force," said Major General Carlito Galvez, who heads the military command in the Western Mindanao region."The main purpose of the offensive is to suppress the lawlessness and to maintain normalcy in Marawi so that our people here, our countrymen, can return, especially by Ramadan."Ramadan, Islam's month of fasting and prayer, began on Saturday and has special significance in Marawi, which has a predominantly Muslim population is a largely Catholic country.The Maute rebels' hold of Marawi City and the government's announcement that Indonesians and Malaysians were among the fighters has raised alarm about the prospect of Islamic State's radical ideology gaining traction Southeast Asia.The Maute have emerged from the glut of bandit and separatist groups in the southern Philippines and are a tactically smart, social media savvy group eager to align with Islamic State militants.Security experts say Mindanao could become a draw for regional extremists and the Maute's alignment with the Islamic State group and its ability to take on the military could support moves to secure funding and recruit foreign and local fighters.A city of 200,000 people, Marawi is mostly deserted, with officials saying "80-90 percent" of the population has been evacuated.Some resident remain in relatively safe neighbors but others are trapped close to the fighters from the Maute group and other militants from the area.Islamic State's Amaq news agency claimed responsibility for the Marawi unrest, although that came more than a day after it started. The military says Maute has yet to be endorsed by Islamic State, or ISIS, as one of its affiliates.