Two car bombs apparently set off by leftist guerrillas exploded in an affluent neighborhood of this capital. Rescue workers said six people were injured. Although there was no claim of responsibility, the bombings Tuesday night appeared to mark an escalation in the employment of the car-bomb tactic by urban commandos. The previous three car bombs this year were primarily incendiary devices. The Farabundo Marti National Liberation Front claimed responsibility for those bombings. A nine-year civil war pits the Marxist-led guerrillas against forces of the U.S.-backed centrist government. The latest bombs were powerful, blowing one vehicle to bits and throwing parts of another onto a 20-foot-high roof. The bombs exploded about two minutes apart. One went off in the parking lot of the ``Biggest'' fast-food hamburger chain, which is Salvadoran-owned but imitates American restaurants. It shattered windows and destroyed part of the roof. The other exploded 200 yards away in front of a complex of boutiques and stores catering primarily to the wealthy in the Escalon neighborhood on San Salvador's western edge. The rebels' clandestine radio indicated in an Oct. 7 broadcast that urban commandos would increase activity in such areas. ``There is no more tranquil rear-guard for the exploiters,'' the broadcast said. ``Because it is not fair that bombs and explosions are heard only in the countryside, in the hamlets of the poor. .. . It is not fair that only the oppressed hear the noise of the war and suffer its consequences. ``The rich are in this war too.'' Rescue worker Miguel Angel Torres said five employees were injured by flying glass at the ``Biggest.'' Another rescue worker said one person was slightly injured by flying glass at the other bombing site. Torres said two of the injured might lose their eyesight. Nicolas Salume, owner of the ``Biggest,'' said about 40 people were inside the building when the bomb went off. He estimated damage at $100,000. A man outside the Biggest said, ``This is a great injustice. It is terrorism.'' He declined to be named, saying he was an industrialist and could become a guerrilla target if publicly identified.