MANILA (Reuters) - Philippine troops on Tuesday killed a pro-Islamic State gunman in the southern city of Marawi, a military official said, eight days after the government declared the end of hostilities. Soldiers have focused on securing Marawi against surviving militant fighters since ending five months of operations against Islamic State-inspired militants who seized control of parts of the city in May, in a bid to win a foothold in the region. The conflict displaced about 350,000 residents and killed more than 1,100 people, mostly militants, stirring concern that the southern Philippines is becoming Islamic State s hub in  Southeast Asia.     The military engaged in a gunfight with one of the suspected remaining gunmen in the main battle area, after foiling his bid to escape, army spokesman Colonel Romeo Brawner said.  We still have to put in troops, because there s a possibility for stragglers,  Brawner told a news conference in Marawi.  In the main battle area, there are many possible hiding spots.  Indonesians, Malaysians and Middle Easterners were among the fighters who flocked to Marawi to support the Islamic State s emirate in Southeast Asia. Thousands of Marawi residents have started returning home, only for some to find dwellings ransacked. Brawner said an army official and five more personnel were detained in barracks after being charged with looting. The main battle area in downtown Marawi remains off limits, pending the removal of booby traps and unexploded ordnance. 