NORTH COUNTY - Federal immigration officials, with assistance from local law enforcement agencies, have arrested 128 Mexican nationals - including 60 with ties to San Diego-area street gangs - during a two-week sweep conducted as part of ongoing nationwide enforcement, authorities said Wednesday.

The initiative by U.S. Immigration and Customs Enforcement - dubbed Operation Community Shield - targeted gang members and associates in North County, including the cities of Vista, San Marcos, Escondido and Oceanside, officials said.

"We think we get a lot of important gang activity by focusing on North County," said Serge Duarte, deputy special agent in charge of the San Diego area. "We think we're getting a big impact on the safety of the community … We were being very specific as to who we're looking for: to ID, locate and arrest hard-core gang members perpetrating crimes in our communities."

The sweep, which ended Friday, was aided by the county Sheriff's Department, Escondido and Oceanside police departments, the county Probation Department and the North County Regional Gang Task Force.

Gang arrests included 17 people in San Marcos, 13 in Escondido, seven in Vista and four in Oceanside; the rest were taken into custody from throughout the rest of the county, Duarte said.

"We see a lot of gang activity in those areas," he said. "We very much want to root out these gang members to bring safety to these communities."

Crimes committed by those taken into custody include narcotics sales, possession of firearms and stolen property, theft, burglary and auto theft, the agent said. One person arrested had three prior convictions for felony battery on a spouse, he added.

"These are clearly people we want out of our neighborhoods," he said.

The effect of immigration-based sweeps on North County gang activity varies city to city, gang to gang, said Lt. Derek Clark, commander of the North County gang task force.

"Some of the gangs are several generations old and the vast majority are individuals that have citizenship or are here legally. But there are several gangs that are substantially (comprised of) aliens," Clark said, adding that San Marcos and Escondido gangs are most heavily affected by immigration enforcement.

According to the agency, about 15 percent to 20 percent of criminal gang members in North County are foreign nationals, some of whom are undocumented.

"The reason for that is it's important for gang members to maintain connection with Mexico for weapons trafficking and narcotics smuggling," Duarte said.

Among those with gang links arrested are 11 people who will be criminally prosecuted, including six who will be prosecuted by the San Diego County district attorney's office on state charges, including drug and weapons violations, authorities said.

The other five are facing federal trial on charges including weapons and re-entry after deportation, Duarte said. They could face up to 10 years in federal prison before being deported, he said.

In addition to those arrested because of gang ties, authorities also arrested 68 other Mexican nationals who are believed to be in the country illegally, including "many with prior criminal convictions," agency spokeswoman Lauren Mack said.

Duarte said he did not know how many had criminal convictions. People arrested in the sweep who are not facing criminal prosecution will be processed to be deported.

"The other aliens were in the wrong place at the wrong time," and may have been with the gang affiliates "in areas known to be gang havens or gang areas" at the time of their arrests, Duarte said.

In Escondido, for example, 35 people were arrested over three days, including four documented gangsters, police said.

"(Police) work basically side by side with (immigration)," Escondido gang investigations Sgt. Mike Kearney said, explaining that during the sweep, immigration agents stepped in when police contacted undocumented "people of interest" during the course of their regular duties.

Authorities have arrested more than 4,900 gang members and associates nationwide since Operation Community Shield was launched in February 2005. Those arrests include more than 270 made in the San Diego area.

- Contact staff writer Sarah Wilkins at (760) 740-3524 or swilkins@nctimes.com.