Federal agents arrested hundreds in a nationwide operation targeting the Mara Salvatrucha, or MS-13, transnational gang between July 15 and Aug. 9, the U.S. Immigration and Customs Enforcement agency, or ICE, said in a press release Friday. The arrests were made by ICE’s Homeland Security Investigations unit, or HSI.

Among the 361 people arrested, 263 were associates or members of 43 different gangs, and 158 of them were associates or members of MS-13. Authorities also arrested 84 nonmembers of gangs who were wanted on criminal charges, as well as 14 others who were detained for immigration violations, ICE said.

“Operations like these are especially rewarding for the men and women of HSI as they know firsthand that they’re playing a critical role in community safety,” HSI Executive Associate Director James Dinkins said.

Of the 361 people arrested, 297 were charged with criminal offenses, including first-degree murder, aggravated assault, assault, firearms possession, aggravated robbery, armed robbery, sexual assault, indecent contact with a minor and kidnapping. During the operation, dubbed Project Razor’s Edge, HSI agents seized 28 firearms, 9.94 kilograms of marijuana, 122.8 grams of cocaine, 771.50 grams of heroin and more than $22,000, ICE said.

Those arrested came from a number of different countries, including Antigua and Barbuda, Brazil, Costa Rica, Cuba, Dominica, Dominican Republic, El Salvador, Guatemala, Honduras, Jamaica, Mexico, Nicaragua, Peru, Trinidad and Tobago, and the U.S., ICE said.

The MS-13 gang was founded in Los Angeles in the 1980s by Salvadoran immigrants fleeing the civil war in El Salvador, as pointed out by the Associated Press via Boston.com last year. It may have begun as a local L.A. gang, but it has spread across the country and into Mexico and Central America.

According to the FBI, MS-13 operates in at least 42 different states and has between 6,000 and 10,000 members. The gang engages in a number of different criminal activities, including drug trafficking, murder, rape, prostitution, robbery, home invasions, kidnapping and others.

Last October, the U.S. Treasury Department declared MS-13 a transnational criminal organization.