MANAGUA, Nicaragua (AP) _ About 1,000 people who occupied a Red Cross building to demand assurances that relatives drafted into the army reserves would not be sent to war zones ended their protest early Saturday.

They had taken over the building Friday morning after the body of a 40- year-old draftee was dumped on the doorstep of his home. People in the town of Boaco, 56 miles noratheast of Managua, gathered to demand an explanation and then marched to the Red Cross office.

Authorities said the man was accidentally shot by another draftee, and the protesters then demanded that conscripts from Boaco serve at posts closer to the town.

The demonstrators, most of whom were women, left the Red Cross building at 4 a.m. after receiving assurances that draftees from their area were not serving in war zones, Monsignor Rafael Obregon of Boaco told The Associated Press by telephone.

The dead recruit, identified as Salvador Fernandez, was one of 400 men taken Wednesday from Boaco, a town of 15,000 residents in a cattle-raising area frequently raided by U.S.-backed rebels battling Nicaragua's left-wing Sandinista government.

Nicaraguan Red Cross official Adolfo Beteta said Fernandez was killed by a stray bullet fired from the rifle of another conscript at a training camp 37 miles northeast of Boaco.

''We do not trust the version of the authorities that the death of the recruit was accidental,'' Aleydac Campos, wife of one of the Boaco draftees, said by telephone before the occupation ended.

Service in the Sandinista army reserves is mandatory for all Nicaraguan men between 24 and 40. The reservists are required to take a 45-day course of basic training and can then return home, ready to be called up in an emergency.

Obregon said Fernandez' wife, Silvia Sanchez Espinoza, told him she was not at home when army personnel brought the body and left it at the doorstep Friday morning.

There were no serious incidents during the protest, Obregon said.

However, Efrain Salinas, the leader of the opposition Social Christian Party in Boaco, was arrested Saturday morning for taking part in the demonstration, according to officials at the party's headquarters.

Demonstrations are banned under a state of emergency decree that has been in force since 1982. The Sandinistas were the major force in the civil war that ousted right-wing President Anastasio Somoza in July 1979.

Nicaragua has an estimated 100,000 people under arms, including the army, reserves and militia.

While many Nicaraguans object to the compulsory military service, there have been few open protests. Two years ago, mothers of young draftees demonstrated in Granada and several other cities and in some cases tried to take their sons off the military trucks.