Specter of Terror in El Salvador. TRADE UNIONS TARGETED. Political violence rises, mainly against less prominent unionists.

CRISTINA GOMEZ turned when she heard her name called but froze when she saw the two armed men approaching. In front of her horrified first-grade students at the John F. Kennedy School in Santa Lucia, on the eastern outskirts of this city, the schoolteacher was forced into a Cherokee Chief with darkened windows, say witnesses who were at the scene. Forty-five minutes later, on the opposite side of the capital, Ms. Gomez was dumped into the street, still apparently alive, and shot four times. She had been tortured with acid poured on her, say witnesses who saw her body.

Gomez's killing April 5 is one example of what many Salvadorans say is an upsurge in political violence and terror that is taking place despite repeated United States warnings about human rights violations. On a visit here Feb. 3, Vice-President Dan Quayle said that a rise in abuses could jeopardize US aid, which totaled $547.5 million in 1988.

What's worse, many observers say the situation could worsen in coming weeks. According to several opposition labor groups, the victory by the rightist Alianza Republicana Nacionalista (ARENA) in the March 19 presidential elections has been interpreted by sectors of the extreme right - whether within the military or within political circles - as a mandate for increased violence against the left. Some observers, including members of the ruling Christian Democratic Party, say the period until the June 1 inauguration of President-elect Alfredo Cristiani could be especially dangerous since any killings that occur during that time will not directly be the responsibility of the new Cristiani government.

Analysts and diplomats here attribute the rising violence to concern within military and rightist ranks about the increased activity of leftist guerrillas in El Salvador's cities. The country's rebel movement, the Farabundo Mart'i National Liberation Front (FMLN), is considered the most powerful in Central America. Along with several recent political initiatives, the FMLN has stepped up a campaign of sabotage and recruitment. (The most audacious recent attack of which the FMLN is suspected was Wednesday's killing of Attorney General Roberto Garc'ia Alvarado.)

The Army, say the analysts and diplomats, is either directly targeting or letting right-wing groups hit the leftist labor movement which it believes is a base for FMLN urban ``commandos.'' In addition, the military is reportedly frustrated by court releases of suspects arrested by police.

Repression of the labor movement is on the rise. Several recent instances of harassment include:

The arrest of at least 15 members of the leftist FENASTRAS labor federation since the start of the year. Two members of its construction workers' union have ``disappeared'' and are presumed dead.

The abduction by heavily armed men of a well-known union leader, Jos'e Tomas Mazariego, of the telephone workers union, ASTTEL, on April 9. Mr. Mazariego, who was released after two days, says he was kept blindfolded while being continually interrogated and beaten.

The bombing of the offices of the main labor opposition group, the National Union of Salvadoran Workers (UNTS), on Feb. 15. A week later, the FENASTRAS union offices were also destroyed by a bomb. The timing of the attack has prompted speculation that it was in retaliation for a guerrilla bombing of the Army's First Brigade the day before.

The Salvadoran military denies responsibility for the violence, and the identity of the abductors or bombers is unknown.

But the international human rights group, Amnesty International, in its report ``El Salvador: `Death Squads' - A Government Strategy'' notes that though the ``government maintains that `death squads-style killings are the work of extremist groups beyond its control ... there is overwhelming evidence to suggest that the squads are made up of regular troops and police - that they form an intrinsic part of the security apparatus.''

The teachers' union claims that the Air Force itself is responsible for the murder of Gomez. Teachers' union president Jorge Morales says that the Air Force patrols the area where Gomez's school is located. ``It's a heavily militarized zone. Nothing could happen there without their permission,'' he says.

Air Force personnel shot and killed Reuters photographer Roberto Navas on the eve of the elections. And on Feb. 22 it appears that Air Force troops killed another teacher. Like Gomez, Miguel Angel Lazo, was a key union organizer in his district, a working-class suburb of Soyapango, about eight miles from the capital's center.

Mr. Lazo, sources say, had been giving a private lesson to a pupil in Soyapango on the same night that left-wing union members held an impromptu street meeting to urge people not to vote in the March 19 elections.

The Air Force, which patrols the entire eastern part of the city, detected the meeting, and sent troops who dispersed it with gunfire. Union sources say Lazo waited until the shooting stopped and then ventured onto the street when he thought it was safe. According to the sources, witnesses saw Lazo stopped by uniformed Air Force troops who accused him of being part of the meeting and started beating him. The next day his tortured body and that of another trade unionist, Carlos Rodriguez, a 22-year-old mechanic, were found on a nearby dirt road.

The case of school teacher Gomez, an activist with the militant teachers' union, ANDES, and a women's group, is typical of the growing number of union activists who are being killed or ``disappeared.''

She was a mid-level activist whose elimination hurts the organization and scares others but isn't prominent enough for her murder to provoke an international outcry.

``She was taken from in front of her school on a busy street in the middle of the day,'' says a foreign human-rights observer. ``With her murder [her killers] were sending a message - that they can get anybody they want, any time they want.''

And this message has sent a chill through this country's union movements, bringing back memories of ``death squad'' atrocities of the early 1980s.