(Associated Press) – UnitedHealth says files with personal information that could cover a “substantial portion of people in America” may have been taken in the cyberattack on its Change Healthcare business.

The company said Monday after markets closed that it sees no signs that doctor charts or full medical histories were released after the attack.

But it may take several months of analysis before UnitedHealth can identify and notify people who were affected.

It has launched a website and call center to answer questions.

The company also is offering free credit monitoring and identity theft protection for people affected by the attack.