Few suspected there was anything to fear from the arrival of the soldiers, whom they believed had been sent to help them.

“It was the first time something like this had happened to us,” Ms. Pérez said.

Mr. González, the 17-year-old who said he had been shocked with electricity, was among the first arrested on Oct. 16. He had been spending the evening burning the family’s trash nearby and had just returned home when, he and his mother said, two soldiers entered the living room and forced him into a jeep.

A five-day ordeal began, he said. At the military barracks, he said, he was stripped naked and photographed. Around 10 p.m. he said, he and five others were taken to a jail where the soldiers tied his arms together, threw him on the ground and stomped on his head.

“If you scream, it will only get worse,” he said one of them had warned.

They stripped him naked again and blindfolded him, he said, and then poured buckets of water onto his face, asking him if he had anything to confess.

“I knew nothing,” he said. “I was just a quiet kid and didn’t run around with anyone.”

In another room, with his eyes covered, he was given electric shocks for about 40 minutes as the soldiers continued to press him about Barlovento’s gangs, he said.

“‘If you are going to kill us, do it now, but don’t keep us suffering this way. Not even dogs would do this,’” he recalled pleading.

Around the same time, security forces were catching others in Barlovento.

On Oct. 15, Carlos Marchena, a 20-year-old who worked at his family’s trucking company, was holding a small party when soldiers entered and forced the men to kneel, according to his widow, Mayerlin Pita. They took the men’s identification cards and loaded them into trucks. It was the last time she saw her husband alive, she said.

The next day, Luis Sanz, a 30-year-old mechanic, was arrested by soldiers, members of his family said. Seven or eight soldiers in ski masks raided the house, his sister Alimirely Sanz said, pushing everyone aside except for Mr. Sanz. Lucía Espinoza, his mother, said she had been thrown to the floor in the melee.

“‘You mothers are the accomplices; you go about aiding and abetting,’” Ms. Espinoza said the soldiers had told her before taking her son away.

The Sanz and Marchena families, along with those of many other people who had been detained, began gathering at a military barracks known as El Café, where they believed their loved ones were being held. For three days, they brought food, water and clothes, handing them to the soldiers in the hope they would pass the items along to the detainees.