Thousands of passengers worldwide were stranded after an IT fault at Germany’s flagship carrier Lufthansa caused flight delays and disruption at airlines across the group.

“There is a group-wide IT system failure,” a Lufthansa spokesperson told Reuters.

Photos and videos from several airports across Germany showed chaos with thousands of stranded passengers waiting to be checked in. Lufthansa Group owns Lufthansa as well as six other airlines including Eurowings, Brussels Airlines, and Swiss and Edelweiss Air.

Lufthansa was working intensively to solve the problem, Bild reported citing a company spokesperson.

A statement on the airline’s website says: “Due to an IT failure many Lufthansa IT systems are currently not working. Because of this reason, passengers must expect disruptions in the flight program and during the check-in process. Further information will be published as soon as possible.

“In case your flight is cancelled we recommend not to proceed to the airport and rebook your flight on our Chatbot.”

The IT system failure comes two days ahead of planned strikes at seven German airports expected to lead to major disruptions.

Scandinavian airline SAS said it was hit by a cyber attack on Tuesday evening and urged customers to refrain from using its app, but later said it had fixed the problem.

Unknown attackers cut cables belonging to Germany’s public railway in December in what was seen as the second act of sabotage against Deutsche Bahn in as many months.

Airlines cancelled more than 1,300 flights and over 10,000 were delayed in the United States last month after the breakdown of a key government computer system.