Immigration enforcement officers are making 7-Eleven stores a target in their crackdown on employers who hire undocumented immigrants.

On Wednesday, agents with U.S. Immigration and Customs Enforcement descended on 98 7-Eleven franchise stores across the country, where they began audits and interviewed employees and managers, according to the agency.

Twenty one people suspected of being in the United States illegally were arrested.

"Today's actions send a strong message to U.S. businesses that hire and employ an illegal workforce: ICE will enforce the law, and if you are found to be breaking the law, you will be held accountable," Thomas Homan, ICE's acting director, said in a statement.

It's the largest worksite enforcement operation against an employer under President Trump, ICE said.

Trump has been tough on immigration during his year in office, and Homan pledged to quadruple workplace crackdowns in October. Still, on Tuesday Trump seemed open to talk of comprehensive immigration reform. He also said he supports a fix for the Deferred Action for Childhood Arrivals program, which protects undocumented immigrants brought to the United States as children from deportation.

Related: Trump contradicts self repeatedly in immigration meeting

ICE said that officers targeted 7-Eleven stores in Washington, D.C., and 17 states: California, Colorado, Delaware, Florida, Illinois, Indiana, Maryland, Michigan, Missouri, Nevada, New Jersey, New York, North Carolina, Oregon, Pennsylvania, Texas and Washington.

7-Eleven, in a statement, sought to distance itself from the hiring practices of store owners.

"7-Eleven franchisees are independent business owners and are solely responsible for their employees including deciding who to hire and verifying their eligibility to work in the United States," the company said. "This means that all store associates in a franchised store are employees of the franchisee and not 7-Eleven Inc."

The company added that it "takes compliance with immigration laws seriously and has terminated the franchise agreements of franchisees convicted of violating these laws."

ICE characterized its action Wednesday as a "follow-up" to actions it took against 7-Eleven franchises in 2013.

Nine franchise owners and managers were arrested for conspiracy to commit wire fraud, use of stolen identities and concealing and harboring employees who were in the country illegally, according to ICE. All but one, who was a fugitive until November 2017, pleaded guilty, and they were forced to pay more than $2.6 million in back wages.

The raids on Wednesday were meant to ensure that "the company has taken the proper steps towards more responsible hiring and employment practices," ICE said.