Two hours later a blast rocked an area near a police outpost in Kadapawan City, North Cotabato. There was one reported casualty in the explosion.
Two children died on arrival at the St. Elizabeth Hospital in General Santos City.
Initial reports said the bomb blew up near a lotto outlet at the ukay-ukay (used clothing) section of the General Santos City public market at 6:10 p.m.
Col. Medardo Geslani, Army-led Task Force Gen. Santos City chief, told The STAR two women were found dead within the perimeter radius of the blast site.
"It is most likely that an improvised explosive device was used," he said.
A man charred beyond recognition was also found near the scene of the bombing, he added.
Geslani said authorities have yet to scour the different hospitals in the city to determine how many were really injured in the explosion.
Reports said more than 10 people were injured in the blast, he added.
Security was tightened in other public areas following reports that similar attacks will take place in other parts of General Santos City, Geslani said.
The bombing took place a few hours after the Joint Coordinating Committee on the Cessation of Hostilities (CCCH) comprised of the government and the Moro Islamic Liberation Front met in General Santos with officials of the Malaysia-led International Monitoring Team.
Ed Gurrea, CCCH government head, said the two panels signed yesterday afternoon an agreement to ensure that no terrorist activity shall take place nationwide.
"We still have to look deeper into the incident because we have just finished our meeting and everything went on fine," he said.
Meanwhile, the military has placed Mindanao under terror alert following the bomb explosion in General Santos City.
Lt. Gen. Rodolfo Obaniana, Armed Forces Eastern Mindanao Command (Eastmincom) chief, said they have been under alert since Wednesday morning, hours before the bombing.
"Our troops are on alert today," he said. "We cannot determine yet as to who could be behind this senseless attack."
Obaniana said the police are investigating what type of bomb was used in the attack.
Authorities are also trying to determine if the attack was aimed at disturbing the ASEAN summit in Cebu.
Police and military forces in Zamboanga City have been alerted to avert any terrorist bombing.
Zamboanga City police director Senior Superintendent Mario Yanga called for an emergency meeting and directed all police forces to be on the lookout for suspicious baggage.
Binang Sali, alias Abu Freedom was believed involved in the kidnapping of Jacqueline and Jeffrey Silbin and a certain Mr. Vergara in July and April, respectively, last year and the liquidation of PNP and Armed Forces of the Philippines (AFP) servicemen detailed in Sulu. Sali has multiple warrants of kidnapping and serious illegal detention and carries a P1 million bounty.
Sali, who was one of the founders and spiritual adviser of the ASG, was slain by army rangers in the jungles of Mount Pula late Tuesday in the southern Island of Jolo. His body and .45 caliber pistol were recovered after the clash but his other followers escaped.
The militarys public information officer Lt. Col. Bartolome Bacarro relayed to reporters that AFP chief of staff Hermogenes Esperon said Salis death would reduce the Abu Sayyafs capability to conduct terrorist attacks.
Bacarro also said Salis death showed the militarys resolve to quash al-Qaeda-linked militants in the South.
"This is just to show that the AFP is bent on putting an end to the days of the ASG and JI, " Baccarro said. With James Mananghaya