A preliminary assessment from U.S. intelligence suggested Iran was behind a cyberattack on Minnesota’s municipal water systems.

Investigators cautioned that the assessment was preliminary. There were no indications that any water supply had been rendered unsafe to drink.

Authorities are looking into whether Iran or hackers associated with the country could be behind the water system attacks, multiple U.S. officials said.

The cyberattacks were aimed at wells and treatment plants, specifically targeting automated systems and plants’ computer systems.

A cyberattack hit Minnesota’s municipal water systems.

State and federal authorities are investigating cyberattacks against remotely controlled water systems in Minnesota.