The suspects worked in San Diego for Continental Maritime, a unit of Northrop Grumman Corp.'s Newport News division. They worked in ship maintenance jobs, including welding, painting, mechanics and pipefitting.

Most were arrested at their homes, said Lauren Mack, a spokeswoman for the Department of Homeland Security. Twelve others who didn't work for the contractor, but were found at the homes, also were arrested on immigration charges, bringing the total number of people detained in the sting to 43.

"We are fully cooperating with the department's investigation," said Rosanne O'Brien, a spokeswoman for Los Angeles-based Northrop Grumman. She declined further comment.

The arrests cap a two-month investigation of Continental Maritime. Authorities said most suspects entered the United States illegally and used counterfeit documents to get hired.

Of the 43 people arrested, 41 were Mexican and two were Colombian. Three were referred to federal prosecutors for charges of re-entering the country after being deported. The others were placed in deportation proceedings.

The sting comes seven months after a dozen San Diego employees of Southwest Marine Inc. were arrested on immigration charges. Their jobs included welding, mechanics and painting.