SAN FRANCISCO (AP) — Immigration agents this week delivered inspection notices to 77 restaurants and other businesses in Northern California and gave them three workdays to prove their employees are authorized to work in the country, authorities confirmed Friday.

U.S. Immigration and Customs Enforcement agents served the notices to businesses in Sacramento, San Jose, San Francisco, and other Northern California cities. No arrests were made, said James Schwab, ICE spokesman in San Francisco.

The inspections heightened already tense relations between federal officials and the state of California over immigration policies.

Sen. Kamala Harris characterized the notices as the latest effort to “punish California.”

“While law enforcement should prioritize dangerous criminals, widespread raids will result in the deportation of those who are living lawful lives and will erode public safety in immigrant communities,” Harris said in a statement.

A notice of inspection asks business owners to produce so-called I-9 forms, which employees are required to fill when first hired to confirm they are legally authorized to work in the country and turn them over to federal authorities within three business days, Schwab said.

If employers don’t comply or have valid forms, they could face fines or criminal prosecution if they are knowingly violating the law, he said.

Schwab said this week’s operation was “focused on protecting jobs for U.S. citizens and others who are lawfully employed, eliminating unfair competitive advantages for companies that hire an illegal workforce, and strengthening public safety and national security.”

The inspections follow last month’s ICE employment audits at about 100 7-Eleven stores in 17 states and the District of Columbia and come as the Trump administration revamps immigration compliance checks aimed at employers.

California Attorney General Xavier Becerra has warned business owners they could face fines of up to $10,000 if they violate a new state law that bars them from turning over workers’ records to federal authorities.

ICE Acting Director Thomas Homan has repeatedly lambasted California over the so-called “sanctuary state” law that strictly limits the cooperation of local law enforcement with federal immigration authorities when they are booked into jail for other reasons. A day after the law took effect, he said ICE will “vastly increase our enforcement footprint in the state of California.”

“California better hold on tight,” he told Fox News Jan. 2. “They’re about to see a lot more special agents, a lot more deportation officers in the state of California. If the politicians in California don’t want to protect their communities, then ICE will.”

Deportation arrests have surged about 40 percent since President Donald Trump took office, even without a budget increase.