The Catholic priest celebrating the early morning Christmas mass was among those wounded, said military spokesman Lieutenant-Colonel Randolf Cabangbang.
Philippine National Police guard the Catholic chapel following an explosion during a Christmas Day mass this morning
About 100 people were at the service in the main police base on the island of Jolo, a stronghold of the Abu Sayyaf, a small Islamist militant group with ties to al Qaeda, Cabangbang added.
'We've placed our troops on alert to prevent similar attacks on churches, shopping malls, parks and transport terminals,' Cabangbang continued.
The Abu Sayyaf has been blamed for several bomb attacks on the Roman Catholic cathedral in Jolo since the early 2000s and for kidnapping priests and nuns.