Story highlights The operation was still ongoing at some sites 6½ hours after it began, official says

ICE investigators raid 13 Danny's Family Car Wash locales in Arizona

It's part of a probe into alleged criminal fraud, identity theft and financial violations

ICE targets "businesses that are a magnet for unauthorized workers," spokesman says

A chain of Phoenix-area car washes that's raised thousands for local charities, including numerous law enforcement agencies, found itself the target of a sweeping raid Saturday by law officers.

Special agents from Immigration and Custom Enforcement's homeland security investigations unit conducted raids at 13 Danny's Family Car Wash locations in central Arizona, plus three locations tied to its outsourced staffing service provider, HR Betty, said ICE spokesman Andrew Munoz.

"We are ... going after businesses that are a magnet for unauthorized workers," Munoz said.

The action came as part of a criminal investigation into alleged criminal fraud, identity theft and financial violations, according to the agency. Few details were immediately available, though more would come out if an indictment in the case is unsealed.

Authorities began executing federal search and arrest warrants around 11 a.m. (2 p.m. ET).

By 5:30 p.m., the operation was still ongoing at some locations, according to Munoz.

The ICE spokesman said he did not know how many people might be arrested. But those who are detained Saturday are expected to make their initial appearances in federal court on Monday.

A phone call placed Saturday afternoon to Danny's Family Companies corporate offices was not immediately returned, and there was no answer when CNN called one of its car wash locations.

Its website , as well as local news reports, tout that Danny's car wash locations have been sites of numerous fund-raisers. A recent one involved members of the Phoenix, Gilbert, Scottsdale police departments, the Maricopa County Sheriff's Office and various fire departments raised $57,000.

The 25-year-old business also has a "Cop Coffee" program, in which law enforcement officers pay 25¢ for any coffee or fountain drink inside a Danny's convenience store.