Hackers with ties to the Russian government successfully altered voter information stole thousands of voter records containing private information during attempts to meddle in the 2016 U.S. presidential election, Time reported.

According to current and former officials who spoke with Time, hackers targeting local election databases were able to modify voter rolls in at least one instance and made off with information including partial Social Security numbers belonging to registered voters.

Read: Did Russia Hack U.S. Election? NSA Details Attempts To Compromise Election Systems, Report Says

Another case found hackers were able to manipulate voter data in a county’s voter database but the changes were discovered and restored, undermining the potential effects of the hack. In that case, the hackers were not identified as Russian agents.

In Illinois, Russian state actors stole more than 90,000 records from the state’s voter rolls. Ninety percent of those records contained driver’s license numbers. Another quarter of them contained the last four digits of the voter’s Social Security number.

While there is an ongoing investigation into ties between members of Donald Trump’s presidential campaign team and members of the Russian government, there is no evidence to suggest the stolen voter records were provided to the Trump campaign—though Congressional investigators are investigating that possibility.

“If any campaign, Trump or otherwise, used inappropriate data the questions are, How did they get it? From whom? And with what level of knowledge?” the former top Democratic staffer on the House Intelligence Committee, Michael Bahar, told TIME. “That is a crux of the investigation."

Read: Can US Elections Be Hacked? Security Experts Call For More Protections Against Election Hacking

The report provides new detail into the scope of Russia’s hacking efforts during the 2016 U.S. presidential campaign. Earlier this month, former FBI director James Comey revealed that “hundreds” if not more than one thousand entities in the U.S. were targeted by Russian hacking efforts.

A National Security Agency (NSA) document published by the Intercept this month provided details into how Russian military-backed hackers targeted U.S. companies that manufacture election software and hardware. The report found the attacks were successful in compromising at least one voting software maker, and that data was used to target at least 122 local election officials across the country in the days leading up to the presidential election.

Following the publication of the NSA document, Senate Intelligence Committee Vice Chairman Mark Warner, D-Va., said Russian attempts to attack U.S. election software and hardware manufacturers were more serious and pervasive than the leak indicated.

This week, the Department of Homeland Security’s acting Director of Cyber Division of the department's Office of Intelligence and Analysis Samuel Liles told the Senate Intelligence Committee the intelligence community found 21 states "were potentially targeted by Russian government-linked cyber actors." At the time, he did not provide details into which states were affected.

Liles said only a small number of the attempted intrusions into the election systems were successful, and none are believed to have led to the manipulation of any results. According to Liles, the U.S. election system is likely to detect any attempt to change votes and said the intelligence community has a "very high level of confidence" in that conclusion.