The explosion – the fifth to rock the country this month – killed a Philippine Marine on guard duty and wounded 18 other people, including two other Marines, Sunday night at Fort Pilar, a historic site in the predominantly Christian port city.
The popular landmark includes the century-old remains of a Spanish fort, a shrine to the Virgin Mary and an open-air worshipping area where Mass is celebrated.
It is a heavily guarded public place with a Marine detachment camped nearby.
"This is the handiwork of terrorists," said Lt. Gen. Narciso Abaya, chief of the military’s Southern Command.
The Roman Catholic Church condemned the attack.
"We are alarmed. This is a series of bombings, and now it is situated in sacred sites," Monsignor Hernando Coronel, secretary general of the Catholic Bishops’ Conference of the Philippines, said. "We are hopeful that the Catholic faithful will continue to hear Mass."
A 13-year-old boy told police that he saw a young man in a black t-shirt and jeans park a pedicab loaded with explosives near the fort’s gate. The suspect left shortly before the bomb went off at around 8 p.m. as the shrine area was crowded with worshippers, he said.
"I saw him. He was about 17 years old. Parked the (pedicab) and left and then there was an explosion. It was the bicycle that exploded," the boy told reporters.
Police said the explosive was hidden in the pedicab’s chassis, which exploded like a pipe bomb.
Police sources said soldiers who rushed to the scene of the blast arrested a Muslim man, aged between 40 and 50, after witnesses saw him drive a pedicab into the gate and leave the vehicle shortly after the explosion. The suspect was later turned over to the police, they said.
The blast demolished stalls selling food, candles and other religious items outside Fort Pilar. Some of the stands were reduced to scraps of splintered wood and twisted plastic. The ground was splattered with blood.
"There was a loud explosion and everybody was screaming," said shrine devotee Fe Sanctuario, who was unhurt. "I knew it was a bomb because the explosion was so loud and many stalls selling religious icons were destroyed."
Military units and police, including plainclothes officers, swiftly fanned out across the city of 600,000 people to deter more possible bombings. Under a steady drizzle, heavily armed soldiers were seen checking abandoned packages at the shrine.
The bombing spooked already nervous stock investors, who began unloading shares when the market opened yesterday, traders said. The main index was down 0.6 percent in early trading, and closed at 1,014.90 The peso, meanwhile, slumped to a fresh 14-month low at 53.46 to $1 in morning trade.
Zamboanga was the target of twin blasts that tore through two department stores last week. Investigators have yet to find the perpetrators of those explosions, which killed seven people and wounded more than 150.
Earlier this month, on Oct. 2, another Zamboanga bombing killed four people, including a US Green Beret commando. Officials blamed that blast — which wounded 25 others, including another American soldier — on the Abu Sayyaf, which Philippine and US officials say is linked to al-Qaeda. The group is considered a terrorist organization by Washington for the kidnapping and murder of US nationals last year.
Zamboanga City Mayor Ma. Clara Lobregat said authorities believed one group was behind all three attacks, and that the group has foreign backing.
"I believe the same group was behind the attack and I think foreign terrorists were aiding them or giving them instructions what to do," Lobregat said.
She urged residents to be vigilant. "Keep calm and don’t panic and we will overcome all these," she said in a radio address.
Chief Inspector Antonio Clarito, operations chief of Zamboanga City police, said he suspected that the Abu Sayyaf was behind Sunday’s bombing.
"The Abu Sayyaf is one of the groups being eyed because there is no other group more capable of doing this than them," Clarito said.
Two more bombs went off last week in Manila metropolitan area. A grenade blew up in Makati City Friday morning, but it didn’t kill or injure anyone.
But later that night, a bomb ripped open a bus, killing two people and wounding in Balintawak, Quezon City. No arrests have been made but police are looking for a man based on a description by a survivor.
The attack prompted police to deploy extra officers around the metropolis to conduct random checks and searches in bus terminals, railway stations, sea ports and airports, as well as in shopping malls.
Marshals were also told to board public buses, with bus firms under orders to deny passage to passengers who refused to submit to body searches and baggage inspections.
In a television address earlier, President Arroyo urged extra vigilance to thwart more attacks, which she said had been carried out by "secretive and determined extremists." She stressed that their numbers were few and have "limited capabilities" to sow fear.
Authorities investigating the bus bombing were looking at the possibility of the involvement of the Muslim militant group Jemaah Islamiyah, believed to be al-Qaeda’s main ally in Southeast Asia.
Jemaah Islamiyah is suspected in the Oct. 12 nightclub bombing in Bali, Indonesia, that killed more than 180 people and injured 300, mostly Australian tourists.
But in an interview with ANC television, National Security Adviser Roilo Golez declined to discuss the possibility that several militant groups might be working together.
"We don’t want to speculate, but we are analyzing this and we are analyzing this very quietly," Golez said. He said investigators already have suspects in mind, but refused to give names.
"We are sharing information with our allies in the region," Golez said. "We take harsh measures to destroy militant cells."
Government spokesman Press Undersecretary Roberto Capco yesterday asked the public to take precautions against terrorist attacks, even as he urged for calm.
"We should not panic. We should not exacerbate the situation by painting it as something that is out of control," Capco said, adding that mayors have already made contingency plans to thwart attacks.
"What we are doing now is intensifying intelligence work so we can trace these people, find them and bring them to justice," he said.
Yesterday morning, Zamboanga was jittery. An unattended package found in an open air food stall created panic, but police said the package was harmless.
Adding to the anxiety were text messages circulating on mobile phones among city residents that another bomb was set to explode before noon yesterday.
Businesses selling cooking gas cylinders added more personnel to guard delivery trucks.
Zamboanga has been a target for attacks after it served as a hub of a joint US-Philippine military campaign earlier this year against the Abu Sayyaf. - Jaime Laude, Roel Pareño, Sandy Araneta, AFP