OSLO (Reuters) - The cyber attack on aluminum producer Norsk Hydro began on Monday evening and escalated during the night, the Norwegian state agency in charge of cyber security said on Tuesday.

“We are helping Norsk Hydro with the handling of the situation, and sharing this information with other sectors in Norway and with our international partners,” said a spokeswoman for the Norwegian National Security Authority (NSM).

She said the damage was still being assessed and that it was too early to say how big it was. She declined to comment on the type of attack.