CÚCUTA, Colombia — Shield in hand, a 21-year-old sergeant major stood fast alongside other soldiers in the Venezuelan national guard Saturday as his countrymen protested and tried to bring humanitarian aid over the border from Colombia.

At first it was peaceful, he said. Then a horde of 30 pro-government Venezuelan loyalists on motorbikes started firing live rounds into crowds of protesters. The tear gas, rocks and rubber bullets came next.

“We realized that it wasn’t what we wanted, so we got out,” said Wilfredo, the sergeant major. Later Saturday night, he and two others walked off base and into Colombia. He spoke on the condition that his full name not be used out of fear of reprisals against his family still in Venezuela.

Authorities here have tallied more than 100 defectors such as Wilfredo since protests at the border turned violent Saturday, leaving four dead and dozens injured. In interviews with The Washington Post, four defectors said they were compelled to leave the country after they were given orders to quash the protests, and one member of the special forces traveled from Caracas to escape during the demonstrations Saturday. They said they also opposed food supplies being rejected and burned while their families went hungry.

Thousands marched at the border, calling for trucks filled with foreign aid be allowed into the country—only to be met with tear gas and rubber bullets. (Jon Gerberg/The Washington Post)

“They just sent us to repress people who in reality weren’t doing anything against anyone,” said Wilfredo, still in uniform Sunday in a Colombian government office in Cúcuta where dozens of Venezuelan defectors were being processed.

The small spike in defections is a boon for the Venezuelan opposition, which stumbled Saturday when its plan to bring aid into Venezuela was violently obstructed by a police force still loyal to President Nicolás Maduro. The U.S.-backed opposition, led by Juan Guaidó, predicted that the armed forces would abandon their orders when presented with food to ease the hunger crisis.

The defectors said that discontent in the ranks is high but that members of the armed forces are bound by fear.

“The order they gave us from high command is that, for whoever takes a step toward the bridge or who tries to leave post, they are authorized to shoot us,” said ­Piñera Martinez, 32, a sergeant deployed in San Antonio.

Martinez said she escaped Sunday morning when she asked for permission to get breakfast off base then diverted course and asked people on a street corner to let her borrow civilian clothes.

They agreed to help and gave her a white shirt and dark pants. She said she walked into the rocky riverbed and through the brush to Colombia. Here, she said, she presented herself to police, who welcomed her and assured her safety as they drove her to a migration authority office.

Jason Caldera, 21, said he knew that the only open exit on base was through a shower room. He took his backpack there early Saturday evening, then waited until 1 a.m., when he slipped out and walked 40 minutes to the border.

He said he put a white T-shirt on a stick and raised it over tall river reeds as he called to Colombian police, who took him in, let him sleep in a facility and fed him that night. In the morning, he said, officials helped him with paperwork to begin his life in the country.

“I don’t know why they want to stop the humanitarian aid,” he said. “The people need it.”

Defectors didn’t come only from nearby bases. William Cancina, a member of the Venezuelan special forces, traveled from Caracas on the pretext of an intelligence mission, he said. But he had made arrangements with contacts in the Colombian police who were waiting for him in the crowd at the Simón Bolívar Bridge on Sunday.

He said he walked calmly past his fellow national police, then through the tear gas to the other side, when Colombian police grabbed him.

“I think 90 percent of the special forces are in favor of this tyranny falling,” he said. “But for fear, terror, doubts, they don’t stop supporting it.”

Sgt. Maj. Mario Velasquez Reyes, 28, said he asked for permission to leave his Caracas base to visit a hospitalized brother. Instead, he headed to the border.

“We aren’t in agreement with this government, which brings hunger, misery, poverty,” he said. “The government has ruined all of Venezuela.”