OLDSMAR, Fla. (WFLA) — A hacker was able to successfully alter the levels of chemicals in Oldsmar’s water supply to ‘potentially damaging’ levels Friday, officials said.

Pinellas County Sheriff Bob Gualtieri said on Friday morning a plant operator at Oldsmar’s water treatment facility noticed someone remotely accessed the computer system he was monitoring.

The computers are set up for allowing remote access to select people to troubleshoot problems, so the operator didn’t think much about the incident.

It happened again that afternoon, however, as the operator could see the mouse moving on the computer screen, opening various software functions that controlled the water being treated in the system.

Gualtieri said the hacker increased the sodium hydroxide levels in the city’s water from 100 parts per million to 11,100 parts per million.

“This is obviously a significant and potentially dangerous increase,” Gualtieri said. “Sodium hydroxide is the main ingredient in liquid drain cleaners. It’s also used to control water acidity and remove metals from drinking water in the water treatment plants.”

Gualtieri said the hacker then exited the system and the operator immediately stabilized the levels back down in the water.

“The public was never in danger,” the sheriff said. “Even if the plant operator had not quickly reversed the increased amount of sodium hydroxide, it would’ve taken between 24 and 36 hours for that water to hit the water supply system.”

Even then, the sheriff said there are redundancies in place where the water would be checked before it was released to the public.

The sheriff’s office does not have a suspect, but Gualtieri said they have a few leads.

They don’t know why Oldsmar was targeted, or if the hacker was foreign or domestic.