Philippine officials say an explosion at a night market in the hometown of the country's president has left up to 10 people dead and several others wounded.

Regional military commander Lt. Gen. Rey Leonardo Guerrero says it was not immediately clear what caused the explosion late Friday in southern Davao City. Police say the blast happened at a massage section of the night market.

President Rodrigo Duterte, who served as a longtime mayor of Davao before assuming the presidency in June, was in Davao but has not issued any statement.

Philippine forces were on alert amid an ongoing military offensive against Abu Sayyaf extremists in southern Sulu province.