The agency said in a statement Friday that the agent was patrolling the Rio Grande in Brownsville, in southernmost Texas, when bees entered his patrol vehicle.
The agent was looking for the origin of the bees Tuesday when he found what he thought was just a bundle of clothing covered in the insects. He then realized it was a woman curled into a ball.
He ordered her to run into his vehicle and discovered she was covering her 8-year-old boy.
WATCH: Man stung to death by bees in Yuma, Arizona
The child began to vomit and the agent rushed the pair to a hospital, where they’re expected to recover.
Authorities say they were travelling from Guatemala.