MANILA, March 28 (Xinhua) -- An explosion on a boat in the southern Zamboanga City has killed five people and injured four others, the Philippine military said Tuesday.

Lt. Cmdr Alvin Dagalea, commander of Coast Station in Zamboanga, said the explosion happened at 8:20 p.m. Monday while the motorized boat was refueling at a private wharf in Zamabianga, a seaside city in the southern Philippines.

Five charred bodies have so far been retrieved from the boat, he said.

He said Philippine Coast Guard authorities are looking into the cause of the explosion.