WASHINGTON — U.S. Attorney General Jeff Sessions on Tuesday cited last week’s quadruple homicide in Central Islip as he vowed a federal crackdown on MS-13 and issued a warning to members of the violent street gang: “We will find you.”

President Donald Trump on Tuesday also touted efforts to combat MS-13 but blamed his predecessor for its spread nationwide.

“The weak illegal immigration policies of the Obama Admin. allowed bad MS 13 gangs to form in cities across U.S.,” he tweeted. “We are removing them fast!”

Though Trump did not directly mention the Long Island slayings, his attorney general listed them as among the most recent acts of violence perpetrated by MS-13, now a key target for the Department of Justice.

“Just a few days ago, law enforcement believes that members of MS-13 murdered four young men and dumped their bodies in a park in Long Island,” Sessions said at a Washington, D.C., meeting on transnational organized crime.

“We will secure our border, expand immigration enforcement and choke off supply lines,” he said. “If you are a gang member, we will find you. . . . We will not concede a single block or street corner to your vicious tactics.”

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Sessions did not announce specific steps in his remarks, but criticized so-called sanctuary cities whose officials may not heed all federal immigration orders.

Sessions had hosted FBI Director James Comey and federal law enforcement officials to generate “concrete ideas” following Trump’s Feb. 9 executive order to focus resources on fighting gangs and cartels and prevent international trafficking.

Local authorities believe MS-13 is responsible for the killings of four young men whose bodies were discovered last Wednesday in a Central Islip park.

“We are in the midst of a war,” Suffolk County Police Commissioner Timothy Sini declared last Thursday.

Rep. Peter King (R-Seaford) in an interview said Suffolk and FBI officials have assured him they are doing all they can in the Central Islip case.

He said of residents, “It should be encouraging for them to realize that Washington is aware of what’s happening.”

Though Trump faulted Obama, information provided by the Department of Justice cited progress made in 2009 and 2010 in disrupting MS-13 operations in target areas through the combined efforts of federal, state and local officials.

MS-13 is composed primarily of immigrants or descendants of immigrants from El Salvador and the street gang has been in the United States since at least the 1980s, originating in Los Angeles, according to the Department of Justice.

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In a “Fox & Friends” interview that aired Tuesday, Trump said Homeland Security Secretary John Kelly is removing those who are in the country illegally and pose a safety threat.

“I’m talking about illegal immigrants that were here that caused tremendous crime that have murdered people, raped people; horrible things have happened,” the president said. “They are getting the hell out, or they are going to prison.”

A tweet later Tuesday from the official account of the president did not mention Obama and instead lauded Sessions’ leadership in working to dismantle transnational gangs.

“I promised to get tough and we are!” it read.

A White House spokesman, asked to elaborate on Trump’s tweet about Obama, said the president was referencing his own executive order.

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Trump was described in a Time magazine profile in December showing the Time reporter an edition of Newsday with a front page on deadly MS-13 violence in Brentwood.

“They come from Central America. They’re tougher than any people you’ve ever met,” he had said.