At least 20 people were injured when an explosion rocked late Saturday a videoke bar located near an Philippine military headquarters in Jolo, Sulu, where some U.S. soldiers are staying for a military exercise, said local television network ABS-CBN News.

Six of the victims were critically injured in hospital, the report said. An earlier report had said 13 people were injured, including six men, five women and two children.

Videoke bars are the most popular entertainment venues in the Philippines where people drink and sing.

The explosion occurred about 100 meters away from the gate of the 104th Brigade of the Philippine Army headquarters, where some U.S. soldiers are based for the Balikatan (shoulder-to shoulder) exercises.

Reports from Sulu said security was tightened around the site of the explosion and an investigation has been launched by police.

Sulu has a dominant Muslim population and some militant groups like the Moro National Liberation Front and Abu Sayyaf group are also reportedly active in Sulu.

The U.S. Embassy in Manila has asked the visiting U.S. troops in Sulu to be prudent and avoid action which could offend the local population.

Source: Xinhua