The main remains of a cargo plane that skidded off a Hong Kong runway and plunged into the sea were recovered from the waters on Sunday, days after the deadly crash.

The Boeing 747, flown by Turkish airline ACT Airlines from Dubai, skidded after landing last Monday and collided with a patrol car, sending both vehicles into the sea. Two workers who were traveling in the vehicle died. The four crew members of the plane were unharmed.

Salvage crews lifted the front of the fuselage, adjusting its position in the air at times before slowly lowering it onto a ship. Before the rescue operation, experts carried out an underwater sonar study and the runway where the accident occurred was temporarily closed.

The plane’s tail and other parts were lifted on Friday, as well as the flight data recorder and cockpit voice recorder. The devices were sent to a laboratory for preliminary examination, according to a government statement.

Investigators were working to determine the cause of the crash. The aircraft was operated on a lease basis by Emirates, a long-haul airline based in Dubai.

Representatives from the US National Transportation Safety Board and Turkey’s Transportation Safety Research Center, along with Boeing experts, are also part of the investigation. The city’s air accident investigation authority said it would release a preliminary report within a month.

Steven Yiu, executive director of airport operations at the airport authority, previously said that weather and runway conditions met standards during the accident, while mechanical and human factors had not yet been investigated.

At a news conference after the incident, Yiu said airport officials gave the plane correct instructions and that there were signs on the runway to guide the planes, the CBS News partner said. bbc news reported. He said the plane went off the runway and crashed into the fence along the road when it collided with the patrol car, which was driving on a road on the opposite side of the fence, according to BBC News.

“Normally, the plane is not supposed to turn towards the sea,” Yiu said at the news conference.