The operations of Norsk Hydro, one of world’s biggest producers of aluminum, have been affected.

On Tuesday, Norsk Hydro, one of the world’s biggest producers of aluminum, stated it was subject to a sustained cyber attack that affected its operations. The development sent its shares plummeting downwards,

“IT-systems in most business areas are impacted and Hydro is switching to manual operations as far as possible. Hydro is working to contain and neutralize the attack, but does not yet know the full extent of the situation,” said Norsk Hydro in a statement.

Norsk Hydro’s website was unavailable on Tuesday.

The company was not immediately available for further comment.

As of 0806 GMT, Hydro’s shares were down by 2.9% and were seen lagging behind the Oslo benchmark index which was up by 0.13%.