Authorities in the U.S. and Central America say they have indicted thousands of violent street gang members since March, including a powerful MS-13 leader who allegedly ordered bloodshed on the East Coast while imprisoned in El Salvador.

Law enforcement officials announced the arrests Friday in Miami, where Justice Department officials are meeting with attorneys general from the so-called Northern Triangle countries of El Salvador, Guatemala and Honduras. The notoriously brutal street gang has roots in Central America and the U.S., and authorities are touting the indictments of 3,800 members in six months as a sign that bolstered cooperation among the countries is paying off.