A submarine-like vessel filled with hundreds of millions of dollars worth of cocaine was seized off the Guatemalan coast, U.S. officials said.

Four suspected smugglers were operating the self-propelled, semi-submersible vessel when it was located and seized on Sunday evening by officials from the U.S. Customs and Border Patrol, U.S. Navy and the U.S. Coast Guard, the Border Patrol said in a news release Wednesday.

When the suspects realized they had been spotted by drug-surveillance aircraft patrolling the eastern Pacific, they scuttled the vessel but were unable to escape.

Coast Guard officials, guided by the reconnaissance plane, intercepted the vessel and detained the reputed smugglers, who were transporting approximately 5.5 tons of cocaine worth $352 million, the Border Patrol said.

Several drug-carrying submarines operated by Colombian drug cartels have been discovered in recent years.