Leftist rebels attacked a military academy in western San Salvador with grenade and mortar fire Friday, wounding two soldiers on the eve of a three-day election truce, the military said.
The attack followed the shooting Thursday of a left-wing parliamentary candidate by alleged rightist activists, blinding her in one eye.
More than 2 million Salvadorans are expected to vote Sunday to renew the 84-seat national assembly and choose mayors in 262 municipalities across the country.
The Farabundo Marti National Liberation Front (FMLN) has announced a unilateral truce starting today to allow for the elections.
The three-day truce is the group's first in 11 years of a civil war that has claimed some 75,000 lives.
The New York-based Americas Watch human rights group, citing recent incidents of political violence, said in a report that campaign-related violence in El Salvador was higher in 1991 than for the country's last election in 1989.
"This is true despite the fact that the (rebel) FMLN has pledged to refrain from military actions that would impede the elections," Americas Watch said.
FMLN rebels fired at least seven mortar shells and rocket-propelled grenades early Friday at the Public Security Academy, a military spokesman said.
Fighting between rebels and government forces has flared in recent days as the army mounted a pre-election push into zones dominated by the FMLN in the north and east of the country.