Tarlac City police chief Superintendent Tito Bayangos said the assumption was made based on the admission of arrested Muslim student Omar Mayumo, who had engaged lawmen in a brief firefight at a bus terminal in Barangay San Nicolas shortly after midnight Wednesday.
One of the suspects companions was killed while five others escaped.
Mayumo, 20, of Makati City, admitted to belonging to a terrorist group called "Haraka," which police believe to be one of the numerous global cells of al-Qaeda, the terror network of Osama bin Laden.
Bayangos noted that the suspect was recruited into Haraka by a cousin last Jan. 23. He and six others received an order last April 30 to go to this city to prepare for the launching of terror activities.
The plan, according to the suspect, was to commandeer tricycles to be used in lobbing grenades at the citys shopping malls and public markets on Labor Day.
The plan was thwarted after police tracked down the seven suspects based on a tip from an asset. One of the suspects was killed after engaging police officers in a gunbattle. Mayumo was nabbed after being cornered by pursuing lawmen.
Police recovered two homemade revolvers, four fragmentation grenades and seven pamphlets on Islam.
Bayangos said Mayumo fits the mold of a typical sleeper, or operatives who settle in a particular place, remaining unnoticed until such time they are called to perform acts of terror.
The police chief also noted that Mayumo could only identify the name of his slain companion as "Khalid."
"This alone shows that the suspects did not know each other," Bayangos said.
Mayumo was taken to the police regional headquarters at Camp Olivas in San Fernando City for further interrogation.
Provincial police director Senior Superintendent Mario San Diego said a manhunt has been launched to track down the five remaining suspects.
He said they are also looking into the mysterious Haraka, which the captured suspect claimed is being led by Saudi national Sheik Hamod, currently a resident of Barangay Mal-ong in Anda, Pangasinan.
It is not clear yet if Haraka is allied with the extremist Abu Sayyaf, which is believed to have links with al-Qaeda.
However, police said Mayumo was a native of Barangay Poblacion in Ipil, a town in Zamboanga del Sur which the Abu Sayyaf had terrorized in 1994.
Bayangos said the police are determining the whereabouts of Hamod and Jamil Camacho, the cousin of Mayumo.
According to intelligence sources, terrorist groups see the city as vital link between Manila to northern Luzon.
Nearly all bus firms servicing passengers from the capital to key cities in the north have terminals in Tarlac. The bus terminal where the suspects were spotted services several bus lines that travel from here to 17 towns of Tarlac as well as neighboring Cabanatuan City in Nueva Ecija.
Crow Valley in the upland western part of Capas town is also the site of ongoing joint RP-US military exercises under Balikatan 02-2, which aims to train Philippine troops in counter-terrorism.
Meanwhile, Bayangos has asked mall owners to beef up their security even as officers have been dispatched to various commercial establishments and other public places in the city. A high alert status has been maintained in the city following Mayumos arrest.
Bayangos also allayed fears of Muslim residents that they would be the subject of military and police surveillance.
"In the first place, initial reports revealed that the Haraka members were not from around here," he said.
There are about 200 Filipino-Muslims living in this city, most of them making a living as traders in the commercial district.
It was in the early 80s when the first Muslims from the south settled here.