MANILA, Philippines -- (UPDATE 3) Police are more inclined to believe the burning of three buses of a transport firm in Cubao, Quezon City, late Wednesday was the handiwork of a group of dismissed employees.

But the military said the New People’s Army (NPA) is the most likely culprit in the attack on the Victory Liner terminal at the corner of New York and Denver Streets, an angle officials of the Quezon City Police District (QCPD) doubt.

Superintendent Asprinio Cabula, QCPD Station 10 commander, on Thursday noted that the 10 armed men who broke into the facility and disarmed the lone watchman did not mention the word "NPA" (New People's Army).

"The men said they were 'taong labas [outsiders].' But they did not tell the security guard that they were NPA," Cabula told the Philippine Daily Inquirer (parent company of INQUIRER.net).

"It is more likely that this is labor-related," he added.

But Armed Forces spokesman Lieutenant Colonel Ernesto Torres Jr. said the attackers’ identifying themselves "taong labas" and accusing the bus firm of not giving them "kung ano gusto namin [what we want]," only bolstered suspicions rebels were responsible for the attack.

Reports on the incident quoted the attackers as saying: "Matagal na kaming galit sa Victory Liner dahil hindi binibigay ang gusto namin [We have been angry at Victory Liner for a long time because they don't give us what we want]."

Torres explained that "taong labas" was a term often used to describe the NPA, while "gusto namin" could be a reference to rebel extortion activities or the collection of so-called "revolutionary taxes."

"Judging from those pronouncements, there is a possibility. Because as they [suspects] claimed they were 'taong labas' and we know for a fact that [that word] is used by the New People's Army," Torres told reporters in Camp Aguinaldo.

Torres said the military is helping the police investigate the incident.

Cabula said they have requested the bus firm's management to give them a copy of the personal data of drivers and conductors who were laid off from their jobs because of various offenses.

He said they received information that the former employees warned the bus company's executives that something would happen to them if they refused the sacked workers’ demands regarding financial benefits.

Cabula, however, said they are not discounting that a group of extortionists could be behind the incident.

According to Cabula, the attackers, armed with handguns, barged into the parking lot at around 11:15 p.m. and disarmed security guard Alex Ranola.

The assailants then herded three other employees of the bus firm to a corner of the garage before they doused kerosene and lacquer thinner onto a bus and set it on fire. Two other buses were partly damaged before firefighters were able to put out the fire around 12:59 a.m. Thursday.

The attackers left on an AUV without license plates.

Torres said he could not immediately recall if communist rebels had struck in the capital in the past.

Asked if the attack, if proven the NPA was behind it, indicated growing rebel strength, Torres said: "We can never tell. We are looking at all possibilities. We don't want to jump into that assessment."