BROWNSVILLE, Texas (ValleyCentral) — U.S. Border Patrol agents found seven spider monkeys during a smuggling attempt in Brownsville.

Agents stationed at Fort Brown made the discovery while making an arrest, according to a Facebook post.

“Extremely proud of our agents for stopping this wildlife smuggling attempt of these critically endangered animals,” the post stated.

The large black backpack had holes throughout so the monkeys could breath. The tiny animals were found huddled together.

According to the World Wildlife organization, black spider monkeys are found in eastern South America in areas north of the Amazon River. They are one of seven species of spider monkeys found in Latin America and one of the largest primate species in South America.

The monkeys were turned over to U.S. Fish and Wildlife.