Rescue teams have recovered the bodies of 31 victims while seven people were still listed as missing Monday following a landslide at the site of a hydropower project in southern China after days of heavy rain, authorities said.

Rescuers aided by experts sent by the central government were searching with tools and sniffer dogs for signs of life, while mechanical diggers hauled away stones and soil, part of a 100,000-cubic-meter (3.5 million-cubic-foot) mountain of rain-saturated debris that buried an office building and a living area for construction workers early Sunday.

Continuing heavy rain in the area was hampering the rescue effort and more evacuations were being organized, the official Xinhua News Agency reported.

"We were asleep when the mountains began to jolt very strongly and before we knew it, sand and mud were flowing into our room," survivor Deng Chunwu told Xinhua. He and three other workers survived by huddling underneath a supporting pole.

Their room was shifted a distance of 10 meters (30 feet) by the flowing mud, Deng said.

A number of other people were being treated for bone fractures and other injures, Xinhua and state broadcaster China Central Television said.

More than 600 rescuers, including firefighters and police, were searching for the missing and attempting to clear sections of roads leading to the site that had been made impassable by mudslides and flooding, hindering efforts to get heavy machinery through.

The project in mountainous Taining county in Fujian province is an extension of the Chitan hydropower station, an affiliate of state-owned Huadian Fuxin Energy Ltd., and was expected to begin operations in August 2017, Xinhua reported.

An official at the county department, who gave only his surname, Wei, said by phone that the cause of the landslide was still unclear, but that the area had seen rainfall in the past few days.

Severe weather, mountainous topography and high population density over much of southern and eastern China make landslides a constant threat. Overdevelopment and shoddy oversight can increase the danger, as was the case in December when 74 people were left dead or missing after a man-made mountain of construction waste collapsed onto buildings in the city of Shenzhen. Police detained 11 people following that accident on suspicion of failing to prevent the disaster.

Heavy rain has affected much of southern China since Wednesday, triggering floods and landslides, disrupting transport and destroying crops.