A military tribunal has sentenced three alleged leftists for their role in a 1985 massacre that killed 13 people, including four U.S. Marines, the Supreme Court announced Saturday.

The court communique said the prison terms ranged from four to 25 years for the three men, who were convicted and sentenced Friday.Thirteen people were killed when gunmen in Salvadoran army uniforms fired their automatic weapons on two outdoor cafes in the fashionable Pink Zone of San Salvador on June 19, 1985.

The dead included four off-duty Marine guards at the U.S. Embassy, two U.S. businessmen, a Chilean, a Guatemalan and five Salvadorans.

The military tribunal convicted William Celio Rivas of helping plan and carry out the killings. He was sentenced to 25 years in prison.

Juan Miguel Garcia received an 11-year prison term and Jose Abraham Dimas Aguilar four years in jail for helping plan the attack.

Armed forces officials say the three belong to the Central American Revolutionary Workers Party, one of five guerrilla armies that make up the rebel Farabundo Marti National Liberation Front.

The Front, which has been at war with a series of U.S.-backed governments for more than a decade, has consistently denied any part in the massacre.

The suspects, whose cases moved slowly through the Salvadoran justice system, were almost set free in a 1988 general amnesty. But then-President Jose Napoleon Duarte bowed to intense pressure from the U.S. government to exempt them from the amnesty.