MANILA, Philippines - A bomb exploded in a market packed with Christmas shoppers Sunday, killing at least 15 people, injuring 58 others and shattering a monthslong lull in terror attacks in the volatile southern Philippines, where Muslim and communist rebels are active.
The homemade bomb, concealed in a box, went off in the meat section of the market in General Santos, about 620 miles south of Manila. Officials immediately bolstered security in the predominantly Christian port city of 500,000 people, fearing more attacks.
President Gloria Macapagal Arroyo said there was no way to justify "this heinous deed."
No one claimed responsibility, and it was not yet clear whether terrorist groups were involved. Muslim and communist rebels both operate in areas around General Santos.
The city had been largely tranquil since a bomb killed 14 people in a shopping mall in 2002. Authorities blamed the Muslim extremist group Abu Sayyaf and a larger separatist group, the Moro Islamic Liberation Front. Some of those arrested are being tried on multiple murder charges.
Police investigator Capt. Maximo Sebastian said three people were killed instantly by Sunday afternoon's blast. Other victims died in hospitals.
"The market was packed with people because there were Christmas flea market stalls there, and the explosion was powerful," Sebastian told The Associated Press by telephone.