Immigration and Customs Enforcement said Thursday that its investigative branch, along with other law enforcement agencies, has arrested 1,378 people across the United States in recent weeks in what officials called the largest anti-gang crackdown in the agency’s history.

More than two-thirds of the people arrested are U.S. citizens, and all but two of those were born in this country, ICE officials said.

The arrests were part of a six-week initiative, from March 26 to May 6, led by ICE’s Homeland Security Investigations unit, which focuses on combating gangs and other criminal activity in the United States and overseas.

Unlike the agency’s immigration section, HSI has broad powers to enforce hundreds of federal laws on crimes such as child exploitation, human smuggling, and drug and weapons trafficking.Its agents routinely arrest U.S. citizens.

Federal officials released the names of only four of the people arrested in the operation, which the agency dubbed Project New Dawn. ICE said it worked with San Antonio police to arrest Gilbert Vasquez III, an alleged associate of the Tango Orejon Gang, on April 5. A search of the house where Vasquez was arrested turned up cocaine, heroin and methamphetamine, four handguns, and over $48,000 in cash, officials said. Three others were arrested at the house, including Brent Reum, an alleged member of the same gang.

(YouTube/ICE)

Olufemi Odeyemi and Brenda Jackson were arrested on April 7 in New Jersey in connection with possession and distribution of heroin, ICE officials said.

ICE acting director Thomas D. Homan and Derek Benner, deputy executive associate director of Homeland Security Investigations, said a total of 1,098 people were arrested on criminal charges as part of the operation. Half were federal offenses. The rest involved state crimes investigated in cooperation with local police, mainly in the Houston, New York, Atlanta and Newark areas.

“Let me be clear that these violent criminal street gangs are the biggest threat facing our communities,” Homan said. “We are not done.”

Of the people arrested on ­criminal charges, 21 face “murder-related” allegations, and seven were arrested on charges of rape and sexual assault.

An additional 280 people face prosecution for alleged civil immigration violations, meaning they were in the United States without permission, and will be processed for deportation, officials said. Of them, 112 are gang affiliates, meaning that ICE had verifiable information that the person was associated with a gang. Sixty-two had no gang ties, officials said.

ICE classifies people as gang members if they admit gang membership or violate federal or state anti-gang laws, or if they meet other criteria “such as having tattoos identifying a specific gang or being identified as a gang member by a reliable source.”

Nationwide, the biggest gangs targeted were the Bloods, Sureños, the Crips and MS-13, an international gang with thousands of members in El Salvador, its command center.

Thomas Homan, ICE acting director, leaves the podium after a news conference on Thursday. (Salwan Georges/The Washington Post)

Fifty-two people were arrested in the District, Virginia and Maryland. Twenty-nine of them allegedly belong to the MS-13 gang.

On April 26, ICE said, it worked with Fairfax County, Va., police to arrest 11 MS-13 gang members at a “stash house” in the Falls Church area. One was arrested on a criminal charge. Two had outstanding deportation orders. The rest were detained for alleged civil immigration violations.

Three of those arrested nationwide had obtained temporary reprieves from deportation under the Obama administration’s Deferred Action for Childhood Arrivals program, which offered protection to illegal immigrants brought here as children.

ICE did not specify the charges the DACA arrestees face, if any. DACA recipients who pose a threat to national security or public safety can lose protected status. One of the three recipients arrested had already lost their status because of a prior criminal conviction, and two are in the process of having it revoked, officials said.

Ten of those arrested nationwide crossed the U.S.-Mexico border as unaccompanied minors. Of these, nine were gang members, all but one belonging to MS-13, officials said.

ICE’s anti-gang initiative has led to more than 47,000 gang-related arrests since it began in 2005, officials said.