Agents from the U.S. Immigration and Customs Enforcement (ICE) searched area El Balazo restaurants, including the Hopyard Road and Wal-Mart shopping center locations, on claims of possible employment violations.
Pleasanton police officers provided assistance, but said they couldn't provide any details because it is not their case.
Capt. Eric Finn said the arrests stem from the business practices of the restaurant chain, which has locations in Pleasanton, Danville, Concord, San Francisco, San Ramon and Lafayette.
Virginia Kice, spokeswoman for ICE, said the 10 locations were searched as part of an ongoing criminal investigation. While she gave no details on how many were arrested, Kice confirmed that arrests were made and the people are being processed and placed in immigration removal.
"Some may be detained and others may be released for humanitarian reasons," she said.
Kice said family members of those arrested can call 415-844-5345 if they have any questions.
"These are not criminal arrests," she added. "The people arrested were taken into custody for being here in violation of our immigration laws."
While not specifically related to this case, Kice said there have been several problems with businesses employing illegal immigrants throughout the country.
"[Illegal immigrants are often exploited by businesses that hire them," she said. "It also gives businesses an unfair economic advantage. Another trend we're finding recently is that increasing numbers of illegal aliens are using the identities and the identity information of U.S. citizens and lawful residents to obtain their jobs. That has serious consequences on the identities they steal."
Enforcement found identity thefts from illegal workers at a poultry processing plant in the Midwest. According to Kice, there were reports of lost medical benefits and a false arrest all resulting from identity thefts.