BEIJING (AP) — The crash of a Boeing 737-800 passenger jet in China’s southwest started a fire big enough to be seen from space and forced rescuers to search a rugged, remote mountainside.

One day after the China Eastern Airlines flight plunged from the sky, there are more questions than answers.

WHAT CAUSED THE CRASH?

The cause is unknown. Flight 5735 was at 29,000 feet (8,800 meters) on Monday afternoon when it went into a dive about an hour into its flight, according to flight-tracking website FlightRadar24.com.

The plane plunged to 7,400 feet (2,200 meters) before regaining about 1,200 feet (360 meters), then dived again. It crashed into the side of a mountain in a remote, forested area outside the city of Wuzhou.

State media and Chinese regulators gave no indication the pilot reported trouble or other information that might shed light on the cause of the disaster. The plane stopped transmitting data 96 seconds after it started to fall.

Rescue workers planned to use drones in the search for the plane’s black boxes, which should contain information from instruments and sound from the cockpit.

Confirming the cause of a plane crash sometimes takes months or years due to the need to gather badly damaged debris and examine specialized technical factors.

HOW MANY PEOPLE WERE ABOARD? DID ANY SURVIVE?

The plane was carrying 123 passengers and nine crew members from the city of Kunming in China's southwest to Guangzhou, an export hub in the southeast.

No survivors have been found as rescuers search the rugged, charred mountainside in the semitropical Guangxi region.

No foreigners are believed to have been on board. Two Chinese companies said their employees were on the flight, including the CFO of Guangzhou-based Dinglong Culture Co. whose interests range from mining to TV and movie production.

Family members gathered in closed-off waiting areas at the airports in both Guangzhou and Kunming. Chinese news reports said five hotels with 700 rooms had been requisitioned closer to the crash site for family members.

IS THIS THE SAME BOEING MODEL INVOLVED IN EARLIER CRASHES THAT RESULTED IN ITS GROUNDING?

No. The plane that crashed was a Boeing 737-800, not the Boeing 737 Max, a newer model that was temporarily grounded worldwide following two deadly crashes in Indonesia in 2018 and Ethiopia in 2019.

The widely used Boeing 737-800 has been flying since 1998 and has an excellent safety record, said Hassan Shahidi, president of the Flight Safety Foundation. They have been involved in 22 accidents that damaged the planes beyond repair and killed 612 people.

China Eastern grounded all of its 737-800s after the crash, China's Transport Ministry said.

The Boeing 737 Max, which entered service in 2017, was grounded by regulators following the two crashes. They were blamed on a computer system that pushed the nose downward in flight and couldn’t be overridden by pilots.

Airlines were allowed to resume using the 737 Max after Boeing redesigned the system in a process overseen by regulators from the United States, Europe, China and the Middle East.