An hour after the first blast, a man claiming to be a member of the Abu Sayyaf terrorist group called the dxKR Radyo Agong radio station in nearby Koronadal City and claimed responsibility for the bombing.
Regional police chief Senior Superintendent Bartolome Baluyot said the first bomb blast occurred in front of the GenSan FitMart shopping mall along Daproza street at around 3:15 p.m.
The bomb, apparently hidden in an empty tricycle, killed children, tricycle drivers, vendors and passersby, Baluyot said.
The casualties were rushed to the Saint Elizabeth Emergency Hospital and other medical centers in the city.
Police identified the dead as Artdee Guinarez, 6; Jack Tumbaga, 7; Hardy Kalunsad, 6; Pearl Ibit Panag, 4; midwife Maroja Lira, school teacher Rosalinda Tablazon and her husband Vicente, Peter Olaer, Jocelyn Umani, Concepcion Panganiban, Jerry Umani, Armando Hamid and Cynthia Guinarez.
Minutes later, two other bombs went off in quick succession near the dxMD Radyo Agong station along the national highway and under the Silway bridge in Barangay Dadiangas West. No casualties were reported in the blasts.
Police found another bomb hidden under a Mitsubishi L-300 van parked across the Fitmart store, but bomb experts safely defused the package.
An hour after the blast, a man who identified himself as "Abu Muslim Al-Ghazie" called the Koronadal City radio station and said his group planted the bombs to refute General Santos City Mayor Pedro Acharon Jr. who supposedly belittled their group.
"Minamaliit kasi ni Mayor Acharon ang aming grupo (Because Mayor Acharon is belittling our group)," the man told the station’s anchor.
Acharon, along with South Cotabato Gov. Daisy Fuentes, was attending a conference of local government officials in Davao City when the blasts occurred.
The man claimed his group was responsible for the fires that hit two shopping malls in the city several weeks ago, killing a security guard and causing some P1.5 billion in property damage.
Police said the man’s group has been extorting fees ranging from P100,000 to P500,000 from big establishments in the city.
But Baluyot said other groups may also be the real perpetrators of the bombings since the blasts came after cellphone text messages circulated in the city, saying 18 bombs had been planted in various places and would explode yesterday.
"We have been receiving intelligence reports and threats of attacks from a group called the Federal Army," Baluyot said, referring to the Indigenous People’s Federalist State Army (IPFSA).
IPFSA, which is supposedly demanding the creation of federal states for Christians, Muslims and indigenous peoples, claimed responsibility for planting at least 13 homemade bombs in various places in Metro Manila, General Santos and Cotabato City last month.
But the authorities belittled the group, saying the bombs were only meant to scare people and not to explode.
The group’s spokesman, whom police identified as a Cotabato City engineer named Rogelio Adamat, said they were not out to scare people and warned the authorities something untoward would happen.
Acharon also received the same text message but made little of it.
"We thought that those were only text messages. We did not realize that such things would really happen," said Fuentes.
"Whatever it is, it is a cowardly act. It hits the defenseless and the innocents. It is terrorism... They should spare the innocents," she added.
However, Baluyot refused to rule out other groups for the bombings since police found it strange the caller would use a name similar to Indonesian national Fathur Rohman al-Ghozi, who was sentenced on Thursday for illegal possession of explosives and forgery of passports.
Police noted that both al-Ghozi and Adamat have been linked to the separatist Moro Islamic Liberation Front (MILF).
Other police sources said Adamat also maintained contact with communist rebels in Central Mindanao, particularly a certain Ike de los Reyes.
De los Reyes was a former ranking member of a splinter group of the communist hit squad Alex Boncayao Brigade (ABB), which was then headed by slain labor leader Felimon "Popoy" Lagman.
De los Reyes later joined another group that broke away from the ABB, the Revolutionary Proletariat Army-Alex Boncayao Brigade (RPA-ABB) and subsequently emerged in Central Mindanao where he supposedly kept contact with Adamat’s group.
Police are still pursuing Adamat, who has been charged with illegal possession of explosives before the Department of Justice.
Intelligence sources said Adamat, 41, was a Tiruray tribesman who has a police record for holding hostage a passerby at Plaza Lawton in Manila several years ago.
Although Adamat had earlier voiced his federalist beliefs, police are still trying to verify the suspect’s true motives in supposedly planting the13 dud bombs.
Police said Adamat was identified through latent fingerprints he left on the bombs and on the manifestos that accompanied them.
The fingerprints matched the ones Adamat submitted to the National Bureau of Investigation (NBI) when he applied for a clearance for a trip to Saudi Arabia sometime in 1989.
Officials records show that Adamat indeed traveled to Saudi Arabia in 1990 and to Malaysia and Pakistan in 1999. — With Edith Regalado