Story highlights Federal agents also seize drugs, firearms and cash

Gang sweep nabs 158 members and associates of notorious MS-13 gang, among others

Immigration agents made the arrests in July and early August

The FBI calls MS-13 an "exceedingly violent" gang

A nationwide sweep by federal agents targeting the violent MS-13 street gang has resulted in hundreds of arrests, including 263 gang members, the U.S. Immigration and Customs Enforcement agency announced Friday.

Those arrested in the July and early August sweep include suspects wanted on murder, assault, sexual assault, robbery and kidnapping charges, among other offenses, ICE said in a news release.

Among those charged are 158 members and associates of MS-13, with 105 others allegedly belonging to other gangs. Authorities arrested 84 non-gang members wanted on criminal charges and 14 people on immigration violations as part of the same sweep, according to the federal agency.

Special agents with ICE's Homeland Security Investigations unit also seized 28 firearms, 10 kilograms of marijuana, 123 grams of cocaine, over 770 grams of heroin and about $22,400 in cash.

Agency officials describe MS-13 -- also known by the name Mara Salvatrucha -- as "one of the most dangerous transnational criminal gangs in the world today."

Salvadoran immigrants fleeing that nation's civil war started MS-13 some years ago in Los Angeles.

Since then, the group has grown to about 10,000 members -- most of them Central and South American immigrants -- operating in largely independent chapters across 42 states, according to the FBI. Authorities allege MS-13 members engage in various criminal activities, including drug trafficking, murder, rape, robbery and other crimes.

And MS-13 extends well beyond the United States, which is why many efforts to combat it have spanned borders.

In 2005, for instance, a two-day operation involving more than 6,400 government agents in the United States, El Salvador, Honduras, Guatemala and Mexico led to 660 arrests. Some 237 of those arrests were in El Salvador, with 73 in the United States.

And last October, President Barack Obama's administration named the organization a transnational criminal enterprise, with the goal of freezing millions of dollars in profits from drug and sex trafficking operations.