BEIJING (AP) — The second “black box” has been recovered from the crash of a China Eastern Boeing 737-800 that killed all 132 people on board last week, Chinese state media said Sunday.

Firefighters taking part in the search found the recorder, an orange cylinder, on a mountain slope about 1.5 meters (5 feet) underground, state broadcaster CCTV said. Experts confirmed it was the second black box.

Searchers had been looking for the flight data recorder after finding the cockpit voice recorder four days ago. The two recorders should help investigators determine what caused the plane to plummet from 29,000 feet (8,800 meters) and into a forested mountainside in southern China.

Flight MU5735 crashed Monday en route from the city of Kunming in southeastern China to Guangzhou, a major city and export manufacturing hub near Hong Kong. An air traffic controller tried to contact the pilots several times after seeing the plane’s altitude drop sharply but got no reply, officials have said.

CCTV and the official Xinhua news agency reported the discovery of the flight data recorder, citing officials.

China Eastern, one of China’s four major airlines, and its subsidiaries have grounded all of their 737-800 aircraft, a total of 223 planes. The carrier said the grounding was a precaution, not a sign that anything was wrong.