Senior Superintendent Bartolome Baluyot, Central Mindanao police director, said police also seized assault rifles and other weapons from the slain gang members.
The three gunmen were aboard two motorcycles when they were intercepted in a police checkpoint at around 4:45 p.m. along the Davao-Cotabato Highway in Barangay West Padaton, Ba-luyot said.
Cotabato police director Superintendent Odelon Ramonedo identified the slain suspects as Abdul Rasbin, Akmad Masbad, and Magdaga Kahil.
They were believed to be men of Kabilo Saguile and Tahir Alonto, both commanders of the Moro Islamic Liberation Front.
Baluyot said the three and two others fired at police when ordered to stop at the checkpoint, triggering a brief gunbattle.
The two other gunmen fled on a motorcycle at the height of the shootout.
Baluyot said that before the encounter, police monitored the five to be heading for Midsayap town from Kidapawan City on an apparent surveillance mission.
North Cotabato Gov. Emmanuel Piñol said the killing of the three Pentagon members indicates that the government’s anti-kidnapping effort in Central Mindanao has borne fruit.
"Our strategy is working and our efforts of tracking down these criminals have slowly paid off," he said. "We are not letting them get away just like that."
Piñol said police tracked down the suspects through his administration’s "Oplan Lambat" which involves the coordination of mayors of towns along the banks of Linguasan Marsh.
"The mayors have been asked to identify the entry and exit points of the kidnappers in the marsh where we have also established chokepoints so they could not use them anymore," he said.
Police believe the three slain gangmen belonged to the group of Saguile and Alonto that kidnapped businesswoman Martina Martin in Libungan town, North Cotabato.
In Sultan Kudarat, the provincial government has asked Muslim preachers for help in negotiating with the Pentagon gang for the release of South Korean treasure hunter Yoon Jae-koon and Filipino hotel owner Oscar Belonio.
Sultan Kudarat police director Superintendent Abubakar Mangelen said prominent members of the Muslim religious community in the province are "initiating" contacts with the kidnappers to convince them to free their two captives.
"We are optimistic that the religious leaders, the local officials, or provincial governor, and Presidential Assistant for Mindanao Jesus Dureza will succeed in working out the release of the victims without any ransom," he said.
Mangelen said the Muslim preachers, whom he refused to identify for security reasons, have sent emissaries to the kidnappers over the weekend.
Yoon and Belonio were snatched last month in Palembang, Sultan Kudarat while surveying the site where Japanese troops are said to have buried treasure at the end of World War II in 1945.
Commander Tigre Jikiri, a leader of the Pentagon gang, is reportedly demanding a P30-million ransom for Jae and Belonio.
The Pentagon gang has been blamed in the past year for snatching Italian Catholic priest Fr. Giuseppe Pierantoni, Canadian Pierre Belanger and several Chinese engineers working on a government irrigation project.
Earlier, President Arroyo ordered the Philippine National Police to "neutralize" the Pentagon kidnap gang so the military could concentrate on the "annihilation" of the Abu Sayyaf. — Edith Regalado, Jaime Laude