ZAMBOANGA CITY (Updated) -- A crude bomb hidden in a motorcycle exploded on Tuesday in Jolo, Sulu, killing two people and wounding 27 others, officials said.

The motorcycle was parked across from a store that was wrecked in the early-morning blast in downtown Jolo, killing the store owner instantly, police and the military said.

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Regional military commander Maj. Gen. Juancho Sabban said the number of fatalities may rise because many of the wounded – including two policemen- are in critical condition.

Most of the wounded were passers-by and students who were on their way to school. For fear of more attacks, authorities have suspended classes in Jolo.

Sabban said the bomb bares the signature of the al-Qaida-linked Abu Sayyaf bandits. He said there were two bombs in the blast site.

Police received information about a bomb and while authorities were detonating it and cleared the area, another bomb hidden in a motorcycle exploded right where the civilians were located, Sabban said.

Early Sunday morning a bomb also exploded outside a Roman Catholic Cathedral in Cotabato City on the mainland of Mindanao, which killed six people and wounded score of others in an attack. The military blamed it on the separatist Moro Islamic Liberation Front (MILF).

The rebels denied it. They have waged a decades-long battle for self-rule in the southern Mindanao region, homeland of Muslims in this predominantly Roman Catholic nation.

Malaysian-brokered peace talks between the government and the rebels collapsed last year when a preliminary deal on an expanded Muslim autonomous region fell apart, sparking deadly clashes that have displaced large numbers of villagers.

Unlike the Moro rebels, who are pursuing on-and-off talks with the government, the Abu Sayyaf is considered a terrorist organization because of its al-Qaida links and many terrorist attacks, including ones on Americans.

Sabban said the bomb blast in Jolo has no relation with the recent blast in Cotabato City.

The Abu Sayyaf Group and its allies, numbering about 400, have turned to kidnappings to make money in recent years, raising concerns among Philippine and US security officials that ransom payments could revive the group, which has been weakened by years of US-backed offensives. (AP/Sunnex)