The Russian hacking of U.S. election systems last year was more widespread than officials have acknowledged publicly, according to a published report.

Russian hackers breached election systems in 39 states, including Illinois, Bloomberg reported Tuesday. In Illinois, it appears hackers tried to delete or change voter data, Bloomberg said based on information from three unnamed sources.

The attacks hit election systems and databases in 39 states in all, according to Bloomberg’s sources.

A recent report by The Intercept, based on a classified National Security Agency report, said Russian hackers attacked a voting-software supplier days before last year’s presidential election. The company involved has contracts in eight states: Illinois, California, Florida, Indiana, New York, North Carolina, Virginia, and West Virginia.

Illinois election officials acknowledged to The Washington Post last year that they discovered “an intrusion” into the state’s election system in July, months before the November election.