Braving sub-zero conditions, thousands of rescuers faced an uphill task on Wednesday finding and treating survivors of a strong earthquake that rocked a remote area in China's northwestern Gansu province more than a day ago.

In Gansu, 113 people had been found dead as of 9 a.m. on Wednesday (0100 GMT), and 782 were injured, authorities said.

The death toll in Qinghai rose to 18 with 198 injured as of 5:30 a.m. on Wednesday.

Seventy-eight people have been found alive in Gansu, where rescue operations ended on Tuesday afternoon, state and local media said, as focus shifted to treating the wounded and resettling residents with the months-long winter at the top of mind.

The magnitude-6.2 earthquake jolted Jishishan county near the border straddling Gansu and Qinghai provinces a minute before midnight on Monday, sending frightened residents out of homes into the cold in the dead of the night.

It damaged roads, power and water lines as well as agricultural production facilities, and triggered landslides and mudslides. Authorities continued to restrict vehicles from entering affected highways.

Emergency responses have been activated, with thousands of personnel from various departments dispatched into the mountainous disaster zone to look for survivors and resettle them.

In Gansu, more than 207,000 homes were wrecked and nearly 15,000 houses collapsed, affecting more than 145,000 people.

More than 128,000 emergency supply items, including tents, quilts, tent lights and folding beds, were delivered while food such as steamed buns and instant noodles were provided to the victims, state television CCTV said.

The quake-stricken area is geographically a transition zone between two plateaus, featuring terrains of altitudes ranging from 1,800 to 4,300 metres (5,906 to 14,108 feet) with "very complex" topography, CCTV said.

Recovery from Monday night's earthquake has been further challenged by the powerful cold snap that has gripped most of China since last week. Temperatures around the quake epicentre in Gansu fell to about minus 15 degrees Celsius (5 degrees Fahrenheit) on Tuesday night.

According to local media citing researchers, people trapped under rubble exposed to minus 10 C conditions without help run the risk of developing hypothermia and may only be able to live for five to 10 hours if uninjured.

Earthquakes are common in provinces such as Gansu, lying on the northeastern boundary of the tectonically active Qinghai-Tibetan plateau. China's deadliest quake in recent decades was in 2008 when a magnitude 8.0 temblor struck Sichuan, killing nearly 70,000 people.

HOMELESS IN WINTER

Those who lost their homes in the earthquake on Monday had few options but to gather in fields, burning wheat straw for warmth. One family of seven took refuge in a car for the night as emergency tents were prioritised for the elderly and young, Beijing Youth Daily reported.

Within 50 km of the epicentre on the side of Qinghai province, the earthquake affected 22 towns and villages, but of that, two villages suffered the worst damage.

Qinghai's Minhe county in the city of Haidong earlier recorded 20 missing people from two villages, where a mudslide swept through half-burying many buildings in brown silt. Search and rescue operations and efforts to resettle residents were complicated as mud blocked main roads, state media said, showing footage of bulldozers clawing through mud and rubble.

"We have prepared coats with extra cotton, like military coats, and then some things to keep warm like heating equipment," said 21-year-old Wu Saying, a rescue volunteer in Haidong.

Resident Du Haiyi said his family home had been completely levelled. The 21-year-old told Reuters he managed to save his mother and 16-year-old sister, who were trapped under debris the night of the quake.

Du, an occasional labourer, said his family of seven has slept exposed to the elements with neither sustenance nor adequate covers, taking shelter in a single tent provided by the local government.

Russian Prime Minister Mikhail Mishustin, who is in Beijing for a state visit since Tuesday, said Russia was willing to provide rescue assistance for the disaster, according to China's needs.

WARY OF AFTERSHOCKS

The freezing cold was not the only concern weighing on rescuers and working groups assessing the situation.

The Gansu Provincial Seismological Bureau said through comprehensive analysis, strong aftershocks of magnitude 5 were still possible around the area in the coming days, based on the characteristics of the Monday quake, historical seismic activity and other factors.

The aftershocks will be closely tracked so as to issue early warnings, official news agency Xinhua cited the bureau's deputy director as saying.

Wu, the volunteer, said villagers whose homes were seriously damaged were given tents. He said he was worried about aftershocks.

By early Wednesday, there were two aftershocks of magnitude 4.0 and above, and eight of magnitude 3.0 and above, China Earthquake Networks Center said.

The quake in Gansu's Jishishan county was logged at a depth of 10 km (6.2 miles), which experts consider shallow. Earthquakes with shallow focal points can easily cause considerable damage to the ground, Xinhua reported citing a senior engineer with the China Seismological Network Center.

Rice, flour and oil supply in Gansu's Jishishan were sufficient at stable market prices, state grain reserves and food processing institutions said, having organised warehouses to deliver emergency supplies to the quake-stricken area. (Reporting by Alessandro Diviggiano and Xiaoyu Yin in Haidong, Liz Lee in Beijing and the Shanghai newsroom; Editing by Sonali Paul and Gerry Doyle)