Flight MU5735 Update: Human Tissue Debris Found, Search Area Expanded For 2nd Black Box

The search area at the crash site of the China Eastern Airlines Flight MU5735 was expanded Thursday, as rescue teams found human tissue debris in the mountains in the southern part of the country, where the Boeing 737-800 went down.

Rescue teams have been using hand tools, metal detectors, drones and sniffer dogs to comb the heavily forested and steep slopes in a bid to retrieve human remains and debris from the crash, Global Times reported.

Authorities are also scrambling to locate the second black box, which could hold key information on what caused the crash. The first black box was found Wednesday.

The passenger jet went down Monday with 132 people on board, while en route to Guangzhou after taking off from Kunming, in the southwest. Finding the second black box and retrieving the data from the already found device would help understand the reason behind the plane's nosedive.

One official said the already-found recorder was so damaged they were unable to tell whether it was the flight data recorder or the cockpit voice recorder.

Flight data revealed the plane plunged out of the sky at close to the speed of sound before slamming into the mountain. The plane was cruising at 29,000 feet when it suddenly nose-dived, and set off a fire in the surrounding forest that could be seen in NASA satellite images.

Video footage widely circulated on Chinese social media on the day of the crash appeared to show the plane in a near-vertical dive.

The flight data provided by an air traffic monitoring service also revealed the plane pulled out of the first dive before another sent it crashing. FlightRadar24 suggested the plane was at an altitude of 29,100 feet when it went into a high-speed dive to 9,075 feet in 2.15 minutes. The plane lost altitude at a maximum rate of about 31,000 feet per minute (348 mph or 560 km/h).

All 132 on board the plane are feared to be dead.

Search operations were halted Wednesday due to weather conditions. However, the teams began their efforts Thursday.

The families of those on board the jetliner have been awaiting answers as to what caused the plane to crash. Authorities have launched an investigation into the crash. However, several theories have emerged, with many saying human involvement could have resulted in the crash. But, International Business Times could not independently confirm these claims.