NEW YORK (CBSNewYork) – Special agents working under a joint law enforcement operation arrested 24 people on Thursday in an effort to stop MS-13 and other criminal gangs operating in Long Island, New York City and the Hudson Valley.

“Operation Matador” has mostly targeted the violent gang MS-13 with 274 arrests, followed by the 18th Street gang with 15 arrests. A total of 475 people have been arrested, with almost half of the total arrests coming from Nassau County.

According to police, the arrests include an MS-13 member who claimed to have been 12-years-old when he first started killing a rival gang members in El Salvador before moving to Long Island and joining gang activities there. He was arrested on unspecified criminal charges and deported.

Other persons arrested included a person wanted by Interpol for killing law enforcement in El Salvador, an MS-13 member arrested in Brentwood who claimed at the age of 13 to have killed three gang members in El Salvador, and an 18th Street Gang member armed with a handgun.

Rival gangs MS-13 and the 18th Street Gang, also known as Barrio 18, both originated from Central American organizations and founded strongholds in U.S. cities, especially Los Angeles and around New York City.

Under “Matador,” criminal and administrative arrests have been made on members from El Salvador, Honduras, Mexico, Guatemala, Ecuador, the Dominican Republic and St. Lucia.

President Donald Trump called out MS-13 as one of the biggest and most violent gangs in the country, responsible for killing 17 people in 17 months on Long Island.

During his State of the Union address in February, Trump told the story of two teenage girls from Brentwood – Kayla Cuevas and Nisa Mickens – who were murdered by alleged gang members using machetes and baseball bats in September 2016.

Last December, five accused MS-13 members in Central Islip faced charges they intended to kidnap and kill a teenager from Brentwood.

Some of those arrested under “Matador” face federal prosecution for re-entry after deportation, a felony. A U.S. Immigration and Customs Enforcement spokesperson said those not being criminally prosecuted will be processed for removal from the United States.