Colorado’s top county official spokesperson said foreign hackers targeted and tampered with equipment from two local water systems in the state last month.

Aly Sullivan said the incident occurred at two private facilities, each serving fewer than 200 people, and had “no impact on public safety or water services.”

Sullivan said the governor’s office “cannot confirm what foreign actors were involved, but is aware of the ongoing efforts of an Iran-backed group across the country to access drinking water and wastewater systems.”

The incidents occurred a few weeks after a wave of cyberattacks on water system equipment in about 12 states and 100 water agencies.