Federal authorities arrested 582 alleged gang members over a two-week period, officials said Monday, targeting an estimated 80 violent groups they say have spawned street crimes across the country.

Homeland Security Secretary Michael Chertoff (search) called the gangs "a threat to our homeland security and ... a very urgent law enforcement priority."

Investigators picked up most of the offenders between July 16 and July 28 on immigration violations for being in the United States illegally. Seventy-six face criminal charges, ranging from illegal possession of a firearm to holding fraudulent documents.

"For too long, these gangs have gone unchecked -- flouting all laws and demonstrating a blatant disregard for public safety," Chertoff said in announcing the arrests by Immigration and Customs Enforcement agents. ICE is an arm of the Homeland Security Department.

Investigators targeted members in 27 states of what they considered to be the most violent street gangs, including Mara Salvatrucha, or MS-13; SureÉnos; the 18th Street Gang; Latin Kings; the Mexican Mafia; Border Brothers; Brown Pride and numerous others.

Many of the arrests came in large urban areas, including 61 in Boston, 28 in Denver, and 23 each in Los Angeles and Detroit. But even smaller cities have been infiltrated by the gangs, the arrests showed, including 42 in Birmingham, Ala., and one each in Grand Rapids, Mich.; Sioux Falls, S.D.; and North Platte, Neb.

The crackdown is part of ICE's ongoing "Operation Community Shield" campaign, targeting gang activity with other federal and state authorities. So far, ICE has made 1,057 arrests as part of the sting.

More than half of them have been members of MS-13, a street gang rooted in Central America where members have been known to behead enemies and attack with grenades and machetes. Federal officials estimate between 8,000 and 10,000 MS-13 members live in 31 states.

"We're just getting started," said ICE investigations chief Marcy Forman.