Central Mindanao regional police chief Senior Superintendent Bartolome Baluyot said the four still-unidentified men were among 11 Abu Sayyaf members who tried to land from a large motorized banca, or kumpit, at Santos Prawn Farm, Purok Royeca in Barangay Bula at around 3:45 a.m.
Baluyot and Col. Pedrito Magsino, commander of the 601st Army Brigade, said they received intelligence reports that some 15 armed men boarded the kumpit at Sarangani province and headed toward Barangay Bula.
Magsino said he coordinated with the police who immediately dispatched units to the area as early as 2 a.m.
As the terrorists approached the shore, the policemen fired warning shots into the air but the suspects opened fire with high-powered rifles and grenade launchers, said General Santos police chief Senior Superintendent Jorge Alquisap.
During the brief firefight, the seven other suspects left their dead companions and turned back their kumpit, managing to escape toward Maasim and Kiamba towns, a known rebel and bandit lair.
The lawmen recovered two M-16 rifles, two caliber .35 revolvers, an improvised M-79 grenade launcher, extortion letters signed by a certain Abu Muslim Al-Ghazie and a letterhead of the 205th Brigade of the Moro Islamic Armed Forces based in Malapatan, Sarangani.
A letter found on the body of one of the slain men was addressed to Hotel Dolores and demanded P500,000 from its owner, fishing magnate Rodrigo Rivera Sr.
"Your business establishment, like other income-generating establishments is operating in our homeland and yet ... it is the Philippine Colonial Government who is benefited by your business," the letter said. Another letter was addressed to the Mercury Drug store.
Al-Ghazie, who signed the letter, had also claimed responsibility for a series of bombings here on April 21 which resulted in the death of 15 people and wounding of scores of others.
Alquisap said the terrorists tried to land in General Santos to launch a simultaneous attack at 2 a.m. of the same day. The suspects were planning to attack the dxES Bombo Radyo, a police station and the Sto. Niño parish church, all in Barangay Bula.
Increased naval patrols had already resulted in preventing the entry of Abu Sayyaf terrorists into Zambonga City after the military clashed with another group of heavily armed men off Barangay Talisayan on Monday evening. The troops also recovered an M16 rifle and a grenade launcher.
Cimatu, who arrived here on Monday after inspecting troops in Datu Odin Sinsuat, Maguindanao, said several security measures have already been implemented and should curb lawlessness in the area.
"We have already planned out things (that) are in place on how to address terrorism in the South. Hopefully, we can resolve this at the earliest time," Cimatu said in a news conference.
He also met with military and local officials, including General Santos City Mayor Pedro Acharon Jr. - With reports from Roel Pareño, Christina Mendez, wire services