All 132 people on board the China Eastern Flight MU5735 have been declared dead after the jetliner crashed into a mountainside in southern China this week, the country’s civil aviation authority said Saturday.

“The identity of 120 victims has been determined by DNA identification,” authorities said. The airline is yet to release the manifest.

The passenger jet went down while en route to Guangzhou after taking off from Kunming, in the southwest. For the last five days, search and rescues teams have been scouring the area to collect debris of the plane and human remains.

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Aviation officials confirmed they had found a black box, which they believe is the cockpit voice recorder. The flight data recorder is yet to be located. 

Finding and retrieving data from the black boxes is key to solve the mystery behind the plane’s nosedive crash. 

Civil Aviation Administration of China, Zhu Tao, told reporters Wednesday that the exterior of the black box was severely damaged, but its data storage unit remained relatively intact. However, it may take 10-15 days to retrieve the data from the black box.

US-based aerospace giant, The Boeing Company on Saturday said a Boeing technical is supporting the National Transportation Safety Board (NTSB) and the Civil Aviation Administration of China (CAAC) in the investigation.

The Boeing 737-800 plunged out of the sky at close to the speed of sound. The plane was cruising at 29,000 feet when it suddenly nose-dived, and set off a fire in the surrounding forest.

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Boeing tweeted Saturday saying, “Boeing will continue to support our airline customers during this difficult time. In addition, a Boeing technical team is supporting the NTSB and the Civil Aviation Administration of China who will lead the investigation.”

The company expressed its deepest condolences to the families of those who lost their loved ones in the crash.

“Following the CAAC’s announcement a short time ago, we extend our deepest condolences for the loss of those on board China Eastern Airlines Flight MU 5735. Our thoughts and prayers are with the passengers and crew, their families, and all those affected by this accident,” The Boeing Company twitter said.