The Coast Guard caught Mexican drug lord Francisco Javier Arellano Felix deep-sea fishing off Mexico, decapitating a murderous cartel that dug smuggling tunnels under the U.S. border, officials said Wednesday.

Arellano Felix, 36, was captured when the crew of the U.S. Coast Guard Cutter Monsoon boarded a U.S.-registered sport fishing boat at 9 a.m. local time Monday about 15 miles off the coast of Mexico’s Baja California peninsula, Coast Guard Commandant Adm. Thad Allen told a news conference.

“We’ve taken the head off the snake,” said Michael Braun, chief of operations for the Drug Enforcement Administration. DEA agents discovered Arellano Felix’s fishing plans and asked the Coast Guard to seize the boat in international waters.

“This is a huge blow” to one of the three largest Mexican drug cartels, Deputy Atty. Gen. Paul McNulty said. However, he added, “much more remains to be done.”

Braun said, “We’re piling on this organization because they are extremely vulnerable right now.”

The cartel was once led by seven brothers and four sisters, but Braun noted that Javier’s brother Ramon was killed in a shootout with police in 2002, his brother Benjamin is in a Mexican prison and brother Eduardo, while at large in Mexico, is not considered “capable of leading the organization at this time.”

“That’s not to say that there aren’t one or more others capable of stepping up and running it,” Braun said.

The cutter Monsoon is towing the fishing boat, the Dock Holiday, back to San Diego where DEA agents will arrest Arellano Felix and others among the eight adults and three juveniles who were captured on board.

Officials anticipated announcing additional charges against the group today.

Arellano Felix is wanted in both the United States and Mexico for his role as leader of the violent and sophisticated Tijuana-based Arellano Felix gang, which McNulty said was blamed in a 2003 U.S. indictment for 20 murders in the U.S. and Mexico.

One law enforcement official said two suspected assassins for the Arellano Felix cartel were among those aboard the Dock Holiday. He requested anonymity because he was speaking before the list of passengers was released officially.

The Arellano Felix gang, along with the Gulf Cartel and the Federacion, are the largest Mexican drug cartels. The Arellano Felix gang is believed to be responsible for the massive drug tunnels discovered last January.

The longest tunnel stretched 2,400 feet from a warehouse near the Tijuana airport to a warehouse in San Diego’s Otay Mesa industrial district. More than 2 tons of marijuana were found in the tunnel. The DEA says the gang is responsible for smuggling tons of marijuana, cocaine, heroin and methamphetamines over the last decade.

In addition, Braun said the Arellano Felix gang was involved in smuggling multiple tons of cocaine from all three major cocaine-producing countries in Latin America – Colombia, Peru and Bolivia. McNulty said the gang received some cocaine from FARC, a leftist revolutionary guerrilla group in Colombia.

Federal drug agents began preparing for the operation 14 months ago after learning that Arellano Felix was planning to go fishing aboard the vessel off La Paz, Mexico, the U.S. officials announced. The agents enlisted the Coast Guard’s help in mounting the operation and were helped throughout by Mexican law enforcement officers, McNulty said.