The 17-year-old son of Philippine News executive Oscar Salvatierra and the youth's girlfriend, 18, have been arrested as suspects in his father's shooting death, Glendale Police Chief David J. Thompson said today.

Thompson said Arnel Salvatierra and Teressa Kay Deburger were taken into custody Thursday night in connection with the incident.

Thompson said police have recovered a gun thought to have been used in the shooting and that the suspects are thought to have sent Salvatierra the death-threat letter he received a day before being found dead Wednesday in a rear bedroom of his home here.

Thompson, who declined to provide more details, said he was releasing the information "to substantiate our statements that Mr. Salvatierra's death was not politically motivated."

"I want to defuse the emotional and political climate surrounding this death," he said.

Asked about a motive for the incident, Thompson said police have found only "a longstanding hatred by the son toward his father, stemming from what, we don't know."

The suspects, Thompson said, "took advantage of the political problems and climate existing in the Philippines to cover their involvement in the homicide."

A naturalized American, Salvatierra, 41, was marketing director of the Los Angeles bureau of the Philippine News, a San Francisco-based weekly newspaper strongly opposed to Philippine President Ferdinand Marcos.

Within hours after Salvatierra's body was found, News Publisher Alex A. Esclamado and other News employes blamed "hit men" employed by Marcos.

The threatening letter, which attacked the newspaper's political position, was composed of pasted-up letters from newspapers and magazines and said Salvatierra had been sentenced to "death by execution."

Thompson said investigators think that the suspects sent it in an effort to divert suspicion from themselves.

Arnel Salvatierra was arrested at the family home at 10 p.m. Thursday, a few hours after Deburger was apprehended on the street outside a friend's house. Thompson said Deburger was "actively an accomplice."

The arrests were made by Glendale detectives "acting on reliable and corroborated statements . . . by an informant," he said.

Arnel, the oldest of Salvatierra's four children, lived with his parents, grandmother, brother and two sisters in a split-level, four-bedroom house in an affluent section of Glendale. The suspects are seniors at Glendale High School.

Vic Pollard, public information director for the Glendale school system, said both are "average students, some Bs, mostly Cs . . . . The boy was a very bright student who didn't assert himself academically. . . . The girl was a very quiet student."

Pollard said Deburger was on the cross-country and track teams and served as manager of the latter. "Both of them were essentially very quiet and nondescript. They blended well into the student body but were not particularly active," he said.

Salvatierra is a minor under California law and is being held at a juvenile detention center in east Los Angeles. Deburger, an adult, is being detained in the Glendale jail. Arraignment is scheduled Monday.

In Washington today, a spokesman for Sen. Alan Cranston (D-Calif.) said there are no plans to withdraw a resolution that was introduced by Cranston and Sen. Edward M. Kennedy (D-Mass.) Thursday and called for a complete investigation into the slaying.

Rep. Stephen J. Solarz (D-N.Y.), chairman of the House subcommittee on Asian and Pacific affairs, who said Wednesday there was "little doubt" the slaying was politically motivated, said today:

"I'm pleased the police have made an arrest. It now appears this may well have been a family feud, rather than a politically motivated assassination."

The arrest, he added, "obviates the concern I and many of my colleagues felt, that this may have involved the Philippine government."

Steve E. Psinakis, an anti-Marcos movement leader whose house was given police protection after the shooting of Salvatierra, called the incident a "tragic family death" and said he was relieved as "one who was supposed to be a prime target" to hear that the Marcos government apparently was not involved