The Michigan State Police Cyber Command Center is investigating to determine exactly how many people doing business with the Unemployment Insurance Agency have been affected by a security breach.
Nearly 1.9 million people are at risk, but the amount will not be known until the investigation is complete.
The potential release of first and last names, Social Security numbers and wage information occurred when a software update was done in October.
State officials say no other personal information, such as birthdates or home addresses, was involved.
The people who had access to the Michigan Data Automated System include employers and other human resources professionals, not the general public.
The Department of Technology, Management and Budget and the Unemployment Insurance Agency has set up a special telephone hotline to answer questions about the issue.
The number is 855-707-8387 and representatives are available weekdays from 8 a.m. to 4 p.m.