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Shirtless, handcuffed and bathed in the searchlights of a helicopter, 14 newly arrested Central American gang members were lined up along a chain-link fence Wednesday and studied by officials from the FBI (search), Homeland Security and California police looking for help with gang problems back home.

As armed SWAT officers stood guard, the Americans grilled the gang members on their U.S. ties and snapped photos of familiar tattoos, the start of a cross-border effort to stop the gangs from moving between Central American and U.S. communities.

Some 50 officials from El Salvador, Honduras, Guatemala and the United States (search) — including nearly 20 U.S. federal agents — were taking part in a three-day conference that included talking to reformed gang members, visiting jails and receiving a behind-the-scenes look at El Salvador's so-called super-hard hand against gangs — including the pre-dawn raid in this town just outside San Salvador (search).

As if to underscore the cross-border nature of the threat, U.S. authorities announced Wednesday they had arrested a gang member wanted in the Dec. 23 massacre of 28 passengers aboard a bus in Honduras. Authorities said the man arrested Feb. 10 in Texas, Ever Anibal Rivera Paz, was the mastermind behind the attack

Also Wednesday, the FBI, California police and Central American authorities announced they will open a liaison office in San Salvador to coordinate anti-gang efforts and share information on the groups.

"There will be no truce in the fight against these criminals," Salvadoran national police commissioner Ricardo Meneses said in announcing the new joint office. "This is a way to do some justice for all the families that have been hurt by them."

The agreement was announced at the end of the conference, which those involved proclaimed a success while pledging to work more closely together. They also announced a follow-up conference in California, but no date was set.

James Jones, a special agent in California with U.S. Homeland Security, said he was impressed with the Salvadoran police and was already setting up contacts to keep tabs on gang members who jump between the two countries.

"I don't think we realized the sophistication they had down here, and they never really reached out to us like this before," said Jones, an Immigration and Customs officer specializing in foreign gangs.

Salvadoran gangs began in Los Angeles among young migrants who moved to California to escape the country's 12-year civil war, which ended in 1992. They spread to Central America in the 1990s as their members were deported, mostly for committing crimes, and many have begun sneaking back into the United States as El Salvador and Honduras launch crackdowns aimed at exterminating the gangs.

They have become increasingly violent, carrying out beheadings and grenade attacks in Central America and hacking their enemies with machetes in cities along the U.S. East Coast. With growing violence in and around Washington, the FBI is launching a national campaign to get better intelligence and centralize U.S. gang investigations at its headquarters.

While Central American governments have tried to link the gangs to terrorism, both U.S. law enforcement and their Central American counterparts say there is no evidence to support those allegations.

Tom Freeman, executive officer for the sheriff's office in Riverside County, California, said the gangs have captured the attention of federal and local officials because they move drugs, arms and people across borders and carry out brazen assaults, such as the bus attack.

"If we don't intervene, are we going to see decapitations?" he asked. "Are we going to see grenade attacks?"

In a crowded room at police headquarters this week, Salvadoran police talked about how gang membership had grown to roughly 10,000 in this country of 6 million people.

They detailed the country's evolving anti-gang program and bused law enforcement officials to a gas station parking lot in the middle of the night to see their efforts firsthand, including the results of their weekly raid — this one in search of some 30 gang members, most of whom are wanted on homicide charges.

While the U.S. officials weren't taken to the actual raids, they were given immediate access to the SWAT teams that carried them out and were shown a few seized guns and ammunition.

Blinking in the beams of flashlights and stripped of their shirts so the visitors could get a better look at their tattoos, the gang members were trucked to a gas station after being pulled from a house.

They smiled and chatted amicably with U.S. officials who quizzed them on their gang affiliations. None readily admitted having been in the United States, but a few had tattoos indicating links to factions known mostly in California. Some also appeared to speak at least some English, and one even gave a federal official the telephone number of a fellow gang member.

For most, it wasn't their first arrest. While some were specifically targeted on homicide charges, others were rounded up on "association" charges, which can yield several years in jail.

"We aren't animals," said Osmedo Artiaga, a 27-year-old member of the MS-18 gang, as officers studied his tattoos, including the likeness of Jennifer Lopez on his right leg.

While police acknowledged the raid — which was covered by a pack of reporters — was a little more hectic than usual, they said they always open their activities to the media and other interested parties. They said they have no money for public education and want to show that they are doing their duty.

The U.S. officials were dazzled.

"I thought it was impressive they went out and rounded up so many," said Martin Ramirez, a deputy from the Orange County, California, sheriff's department.