Its members are mostly Salvadoran nationals or first-generation Salvadoran-Americans. But the group also consists of Hondurans, Guatemalans, Mexicans, and other Central and South American immigrants, according to the FBI.

MS-13 is a notorious international street gang that has been tied to a wide range of crimes, including violent activity, according to the FBI. One of the largest criminal organizations in the United States, it is also sometimes called Mara Salvatrucha.

The word Mara in El Salvador means gang, according to court documents filed by prosecutors in the major crackdown announced Friday in Boston. The first five letters of Salvatrucha are an abbreviation for Salvadoran, and the last six letters are a slang term for “fear us, look out, or heads up,” court documents say.


Where does the gang operate?

Within the US, MS-13 operates in at least 46 states and in Washington D.C., including Massachusetts, according to court documents. And the gang’s presence has been growing.

Court documents filed by prosecutors in Friday’s case say that members operate throughout the state, including in East Boston, Everett, Chelsea, Somerville, Lynn, and Revere.

The FBI has said in recent years that the gang poses the highest threats in the western and northeastern parts of the US — areas that have large Salvadoran populations.

How many members do they have?

There are believed to be more than 6,000 members in the United States and more than 30,000 worldwide — mostly in El Salvador, Mexico, Honduras, and Guatemala, according to court documents.

They often target middle and high school students for recruitment, the FBI says.

For example, court documents say that students as young as 14 and 15 from Chelsea High School, Everett High School, and East Boston High School have been recruited.

What activities are MS-13 members involved in?

The gang has been tied to “drug distribution, murder, rape, prostitution, robbery, home invasions, immigration offenses, kidnapping, carjackings/auto thefts, and vandalism,” the FBI says. “While most of the violence is directed toward other MS-13 members or rival street gangs, innocent citizens often get caught in the crossfire.”


Their motto is “mata, viola, controla,” or “kill, rape, control,” officials say.

How are members identified?

MS-13 members often have tattoos signifying their membership, court documents say.

The gang’s colors are generally blue and white, sometimes with the number 13. They often wear Nike Cortez sneakers in blue or white, court records say. They do not wear red, which is the color of their main rival gang, the 18th Street Gang.

The gang sometimes uses graffiti to mark territory, court records say.

What are the origins of the gang?

MS-13 originated in Los Angeles in the 1980s. Its members migrated eastward from there, forming cliques that for the most part operate independently, the FBI says.

Some of the cliques known locally include the East Boston Loco Salvatrucha, the Chelsea Loco Salvatrucha, and the Everett Loco Salvatrucha, according to court records.

What is the FBI doing about the gang?

In late 2004, the FBI formed a special national task force to focus on efforts to combat the MS-13 gang.

”This intelligence-driven task force combines the expertise, resources, and jurisdiction of federal agencies that investigate this violent international street gang,” the FBI says.

“It focuses on maximizing the flow of information and intelligence, coordinating investigations nationally and internationally, and helping state and local law enforcement improve operations and prosecutions targeting MS-13.”

Matt Rocheleau can be reached at matthew.rocheleau@globe.com. Follow him on Twitter @mrochele