MANILA: A powerful blast killed at least five people and wounded three near a school on a southern island in the Philippines Thursday, a marine general said. No has claimed responsibility for the attack but a small band of militants with close ties to Al-Qaeda and regional network Jemaah Islamiah (JI) operates on the island, Brigadier General Romeo Tanalgo, marine commander, said. The blast occurred as military aircraft fired rockets and dropped assault troops Thursday on a southern island where an al-Qaida-linked Abu Sayyaf commander wanted by Washington has been sighted with his men, officials said. Troops launched the assault at dawn after detecting the presence of Khair Mundos, his deputy Puruji Indama and about 15 Abu Sayyaf fighters in a mangrove area on Sacol island near Zamboanga city, military spokesman Lt. Col. Randolph Cabangbang said. The notorious Abu Sayyaf group has been blamed for deadly bomb attacks, ransom kidnappings and beheadings. It was founded in the early 1990s on nearby Basilan Island, near Zamboanga, a bustling region 540 miles (860 kilometers) south of Manila where American counterterrorism troops have been stationed for a decade. Cabangbang said it was not immediately clear if anyone was killed or captured, adding the assault was continuing several hours after it started in an area that was far from communities. Sacol is one of about two dozen islands off Zamboanga city. Military officials became concerned after receiving information that Mundos, who leads an Abu Sayyaf faction in Basilan province, has been spotted in Sacol, which is about 30 minutes by boat from Zamboanga. The Abu Sayyaf has carried out deadly bombings in the port city in the past. “It's actually alarming because they were near the city,” Cabangbang said. “We immediately undertook an operation to thwart whatever plans they have.” Washington has blacklisted the Abu Sayyaf as a terrorist group and blamed it for deadly attacks on American troops and civilians in the southern Philippines. Zamboanga Mayor Celso Lobregat said the military assault was so secretive he and other officials were not notified, prompting him to call Defense Secretary Voltaire Gazmin to check what was going on. The State Department announced a $500,000 reward in 2009 for the killing or capture of Mundos. U.S. authorities said he has worked as a financier of the Abu Sayyaf. He has led one of four key Abu Sayyaf factions in the south and is known to have active links with members of the Southeast Asian militant network Jemaah Islamiyah. Indama has been linked by the military to beheadings and kidnappings for ransom in Zamboanga and Basilan. A confidential government security report seen by The Associated Press last month said that the Abu Sayyaf, believed to include 410 fighters, was hounded by funding problems and resorted to kidnapping even poor victims to raise ransom money. The militants were using cheaper but more lethal bombs than previously, the report said.