Just an hour after taking off, a China Eastern Plane was forced to return to Sydney airport after a mid-air technical failure, BBC reported. Images circulated on social media showed a large hole in the flight’s left engine casing.

China Eastern Airlines’ General Manager Kathy Zhang said the flight had landed safely and everyone on board the plane, including the passengers and the crew members, were safe. The Airbus A330-200 twin jet has a Trent 700 series engines that was manufactured by Rolls-Royce.

Zhang said a full investigation would require involvement from Australia and China. “The engine for the aircraft is a big issue so we need to investigate with the governments, with the Rolls Royce company and with our headquarters as well,” she said, according to Reuters.

“We are aware of the incident and will be working closely with our customer and relevant partners to understand the cause of the issue,” an unidentified Rolls-Royce spokesperson told Reuters.

Passengers on board flight MU736 said shortly after the take-off, they had heard a loud sound coming from the left engine. Some passengers said there was a burning smell in the flight, reported Yahoo7 News. “The moment we took off, the wing to my left just started making massive amount of noise,” a passenger told Yahoo7 News.

The passengers who had to wait back at Sydney airport are scheduled to leave the city on Monday, China Eastern Airlines said in a statement.