A water utility that serves Montgomery and Prince George’s counties in Maryland was the target of a ransomware attack that compromised some internal files.

WSSC Water said in a news release the attack “impacted a portion of our network that operates non-essential business systems” on May 24.

The virus was removed within hours of being discovered, and it had no impact on water services or quality, the company said.

“WSSC Water continues to produce and deliver safe, clean water to 1.8 million customers in Montgomery and Prince George’s counties and at no time was the quality or reliability of our drinking water in jeopardy,” WSSC Water Police and Homeland Security Director David McDonough said in a statement.

The water treatment plants are not connected to the internet to safeguard against these types of breaches.

WSSC alerted federal, state and local authorities of the attack, and is conducting its own investigation as well.

WSSC said they will notify any individuals whose personal information was exposed during the attack and will offer five years of credit monitoring and $1 million in identity theft insurance.