Authorities were looking into the cause of a forest fire on the mountain ranges of Mt. Mangaturing and Mt. Piagayungan in the boundaries of Lanao del Sur in Maguindanao and North Cotabato on Thursday night. The Provincial Disaster Risk Reduction and Management Council of Lanao del Sur said the fire started about 10 p.m., and heavy billows of smoke were still observed on Friday. PDRRMC officer Saripada Lucman Pacasum, Jr., said fire trucks and rescue vehicles had a hard time entering the fire area because of its high elevation and it is a five-hour walk from the ground. Col. Roseller Murillo of the 103rd Infantry Brigade said they were also looking at animal hunters who could have set fire to the grasses.