LOS ANGELES -- Hundreds of people are under arrest following a massive sweep aimed at suspected illegal immigrants with criminal records.

More than 400 agents with the Immigration and Customs Enforcement ( ICE) along with local law enforcement officers fanned out across California in a three day search for immigrants with criminal histories who are not supposed to be in the United States.

280 suspects with criminal records were arrested in the sweep, another six people who are under deportation orders were also arrested, according to ICE officials. 167 foreign nationals with criminal records were taken into custody in the Southern California area.

More than 80 percent of the people arrested had prior convictions for serious or violent crimes, such as rape by force, armed robbery and assault with a deadly weapon. Also among those arrested were 30 convicted sex offenders, many of whose crimes involved sexual assaults on children.

Of those arrested, at least 100 have already been removed from the country, ICE said.

At a news conference today in downtown Los Angeles, Homeland Security Assistant Secretary for ICE John Morton announced the results of the operation, which involved more than 400 agents and officers from ICE, the U.S. Marshals Service, as well as several other state and local agencies.

"If you commit crimes in this country and come back, we're going to arrest you, prosecute you, put you in federal prison -- then deport you," Morton said.

A conviction for felony re-entry carries a penalty of up to 20 years in federal prison.

Of those taken into custody, the Los Angeles area recorded 96 arrests, followed by San Diego and Imperial counties collectively with 71. The arrestees mostly hail from Mexico and Central America, Morton said.

Among the arrestees being federally prosecuted is a previously deported Guatemalan national with ties to a Los Angeles street gang whose criminal history includes a prior conviction for first-degree robbery. Ulises Vazuiz Arucha, 37, was arrested by ICE officers Tuesday in Reseda.

Also facing felony re-entry charges is Ignacio Camacho-Madrigal, 43, a Mexican national formerly convicted of committing a lewd act on a child under 14. Camacho-Madrigal was arrested Tuesday in Rialto.

Other arrests took place in Glendale, West Hills, Downey, Ontario and Highland, ICE noted.

"These are people we don't want walking our streets," Morton said.

The foreign nationals detained during the operation who are not being criminally prosecuted will be processed administratively for removal from the United States, ICE said.

Those who have outstanding orders of deportation, or who returned to the United States illegally after being deported, are subject to immediate removal from the country. The remaining arrestees were in ICE custody awaiting a hearing before an immigration judge, or pending travel arrangements for removal in the near future, ICE said.

ICE spokeswoman Virginia Kice says the operation is the agency's biggest such crackdown so far in local communities.