China Eastern Airlines Crash: One of Plane’s Black Boxes Is Found

The plane, operated by

China Eastern Airlines,

was carrying 132 people when it plunged to the ground on Monday in a rural part of China’s Guangxi region.

The two black boxes store vital information and typically provide accident investigations the best information about what caused a plane to go down. The devices, both bright orange, are hardened to withstand even significant impact and their data can often be useful to investigators even if the boxes are damaged.

Heavy rain hampered search efforts on Wednesday. More than 2,000 rescuers, armed with shovels and flashlights, combed through mountainous terrain and began discovering human remains at the crash site.

The wreckage of the plane was strewn across a hilly, forested area. An army of rescuers—including soldiers and firefighters—and excavators dug into the land where the crash’s impact wiped out trees and a terraced field, video from state broadcaster China Central Television showed.

The rain soaked the crash site, forcing rescuers to suspend their effort, CCTV reported, adding that the smell of fuel still lingered at the scene. The broadcaster said rescuers warned the rain could cause small-scale landslides.

The plane was carrying nine crew members and 123 passengers. With no survivors found, it could be China’s worst plane crash in almost three decades.

Ou Ling, a fire department official in Wuzhou, a city in the Guangxi region near the crash site, told CCTV on Tuesday that human remains have been found. Details about any recovery of bodies remained scarce in Chinese media.

Mr. Ou said the narrow paths to the crash site have prevented larger rescue equipment from entering, adding that the lack of lighting facilities in the mountains—especially at night—has complicated their mission, according to state media.

A spokesman for China’s airline regulator, Zhu Tao, said at a briefing late Tuesday that the severely damaged jet has made the investigation difficult and the cause of the crash couldn’t yet be determined.

The plane, a Boeing 737-800, was suitable for flying and reported no technical issues before takeoff and its aircrew were in good health and met flying requirements, Chinese officials said Tuesday. China Eastern had been in contact with the family members of all 123 passengers onboard, according to Sun Shiying, chairman of the airline’s subsidiary branch based in southwestern China’s Yunnan province.

Boeing has said it was working with the airline and its experts are prepared to assist with the investigation.

—Rachel Liang and Qianwei Zhang contributed to this article.

Write to Elaine Yu at elaine.yu@wsj.com