LHASA -- A major landslide hit a mining area in Tibet Autonomous Region on Friday morning, burying 83 workers, local authorities said.

The landslide happened at about 6 a.m. in Maizhokunggar County of Lhasa, the regional capital. The victims were workers from Tibet Huatailong Mining Development Co. Ltd, a subsidiary of the China National Gold Group Corporation.

The affected area of the landslide is 3 kilometers long, with about 2 million cubic meters of mud, rock and debris, a Xinhua reporter said from the disaster site.

More than 1,000 rescuers, including police, firefighters and medical personnel, are working at the site, which is at an altitude of 4,600 meters.

Villagers living nearby told Xinhua that the landslide struck suddenly, bringing massive rocks down to smash the workers' camp area in early morning.

A mass of rolling rock from the mountaintop sliced a big excavator in two parts, a witness told Xinhua.

Two of the buried workers are local Tibetans and others were recruited mainly from neighboring provinces of Yunnan, Guizhou and Sichuan.

Five excavators, five pick-up trucks and an SUV were also buried in the debris, said Zou Yuming, deputy head of the Maizhokunggar County government.

About 200 large vehicles and equipment, 15 sniffer dogs and 15 life-detector machines are being used in the rescue.

The rescue will be very difficult due to the size of the affected area, said an official from the regional fire department.

Chinese President Xi Jinping and Premier Li Keqiang on Friday ordered top efforts to rescue the buried workers.

Xi, who is paying state visits abroad, and Li, respectively, have told local authorities to spare no efforts to rescue the buried and prevent secondary disasters.

They also urged to lose no time to confirm the number of buried workers and determine the cause of the landslide.

A work team led by officials from the State Administration of Work Safety, Ministry of Land and Resources and State-owned Assets Supervision and Administration Commission is rushing to the accident site to guide rescue efforts.

The National Disaster Reduction Commission and the Ministry of Civil Affairs initiated an emergency response to the Tibet landslide at 10 p.m. and sent work teams led by Vice Minister of Civil Affairs Jiang Li to aid in disaster relief, according to a statement posted on the Civil Affairs Ministry's website at midnight.

The site of the accident is within the Jiama Copper Gold Polymetallic Mine, about 68 kilometers from Lhasa.

The company's mining permit covers a total area of 144 square kilometers at an altitude of 4,000 to 5,407 meters, Jiang Liangyou, board chairman and Party secretary of the owner of the mine, Tibet Huatailong Mining Development Co. Ltd, told Xinhua last June.

First-phase production of the mine started in July 2010 with a total investment of 3.5 billion yuan (558 million U.S. dollars), and the largest copper gold polymetallic mine in Tibet specializes in the exploitation and processing of six metals -- namely, copper, lead, zinc, gold, silver and molybdenum, Jiang said.

Located within the Gangdise Copper Metallogeny Belt in central Tibet, the Jiama project has been developing amid disputes. Before the mining area was taken over by Huatailong in late 2009, a dozen private miners were caught up in a rat race for the rich ore supplies, ignoring their responsibilities to the local community and environment.