MANILA: At least nine people were killed and more than 20 seriously wounded Monday in a bomb blast on the restive southern Philippine island of Jolo, police and witnesses said. "As of the moment, we have an initial nine dead on the spot," Jolo provincial police chief Ahiron Ajirin told reporters. The bomb was planted on the ground floor of a two-storey building along a busy street in the centre of Jolo town. Those killed were mostly employees working in a cooperative there, he said. Police set up road blocks around the town and many businesses closed early following the blast. An AFP reporter said he saw more than 20 people with severe burns taken to Jolo's provincial hospital. Part of the building's facade fell to the ground after the explosion, the second deadly bomb attack to hit the area this year. No group has claimed responsibility. Ajirin said one man had been taken in for questioning but would not say if he was a suspect.