Updated

Two suspects are in custody after an off-duty Border Patrol agent and his father were shot during a robbery as they fished in South Texas late Sunday.

Willacy County Sheriff Larry Spence told FoxNews.com that a family of four adults and three children were fishing for gar near Santa Monica when the two suspects saw them from the roadway and decided to rob them.

“The whole family was out there, the mother, the father, his wife, his parents, and some children,” Spence said. “A vehicle goes past and then noticed them, turns around and comes back. We’re still sorting out what happened, but from what they said, they told everybody to get on the ground and tried to rob them.”

Spence, who added that the robbery “fits a pattern” of similar recent holdups in the area, said the off-duty unidentified agent was armed with a gun in his holster. The suspects apparently opened fire after noticing the weapon, he said.

“I don’t think they knew he was a Border Patrol agent,” Spence told FoxNews.com. “It surprised them when they found out he was armed as well.”

The identity of the agent was not immediately released. The second victim is believed to be the agent’s father, who was shot in the hip, Spence said.

The suspects were later apprehended in a shed behind a home in nearby Sebastian.

U.S. Customs and Border Protection officials did not return messages seeking comment Monday.

FoxNews.com's Joshua Rhett Miller contributed to this report.