ZURICH, Switzerland - Ten passengers needed medical treatment after a Swiss airlines flight was forced to make an emergency landing due to smoke in the cockpit and cabin, the company said on Monday.

One cabin crew member was airlifted to hospital by helicopter after the plane landed in the Austrian city of Graz. Their condition was not immediately known but the airline said it was "deeply concerned".

Four other crew members were treated by medics, it added in a statement.

The Airbus 220-300 aircraft, which had 74 passengers and five crew on board, was flying from Bucharest to Zurich when it was forced to land in Graz due to "engine issues and the detection of smoke in both the cabin and the cockpit".

"Our thoughts are with the passengers and our colleagues who had to experience this incident," Swiss said.

"We remain in close contact with the local authorities and are working to determine the cause of the incident and plan the next steps."

Graz Airport was closed while the plane was still on the runway.

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© Agence France-Presse