Rescue workers conduct search and rescue operations at Kangdiao village following the earthquake in Gansu, China. Reuters

A magnitude-6.2 earthquake jolted a remote and mountainous county on the northern edge of the Qinghai-Tibetan plateau just before midnight on Monday, killing at least 118 people and injuring hundreds, according to Chinese state media.

Authorities have mobilised an array of emergency responses, but rescue work could prove challenging in subzero temperatures. Most of China is grappling with freezing temperatures as a cold wave that started last week continued to sweep through the country.

Twenty people have been reported missing in the quake's aftermath after hours of rescue and relief efforts that began before sunrise, according to state media.

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

The epicentre of the latest quake was 5 km from the border between Gansu and a neighbouring province. Strong tremors were felt in many parts of Qinghai province, the official Xinhua news agency said.

A government worker looks at the debris of a house brought down by the earthquake in China. AP

The quake struck Jishishan county in China's northwestern province of Gansu at 11:59 p.m. local time (1559 GMT) on Monday at a depth of 10 km (6.2 miles), according to China earthquake Networks Center (CENC).

In Gansu, 105 were killed in the quake as of 7:50am on Tuesday (2350 GMT Monday), and of 397 injured as of 9:30 a.m., 16 were in critical condition, provincial authorities told a news conference.

The death tally in Qinghai rose to at least 13 with 182 injured, state media reported.

About 2,200 rescue personnel from the provincial fire department and 900 from the forest brigade, as well as 260 professional emergency rescue personnel, were dispatched to the disaster zone, Xinhua reported, adding that the military and police were also engaged in rescue work.

China's Ministry of Emergency Management upgraded its earthquake emergency response to second-highest level, Xinhua reported. Its national health commission sent a team of medical experts and coordinated emergency teams from other provinces.

The province, which has allocated 20 million yuan ($2.8 million) to the local government for emergency response work, also sent supplies that included 2,600 cotton tents, 10,400 folding beds, 10,400 quilts, 10,400 cotton mattresses, and 1,000 sets of stoves.

Local authorities have also imposed traffic restrictions into Jishishan for until rescue work is done, CCTV said. Social volunteers are requested not to enter the disaster zone as well, local media said.

Race against the cold

As the disaster area is in a high-altitude region where the weather is cold, rescue efforts are working to prevent secondary disasters caused by factors beyond the quake, Xinhua said.

Residents gather outdoors the morning after an earthquake in Dahejia, Jishishan County, China, on Tuesday. AFP

The temperature in Linxia, Gansu, near where the quake occurred, was about minus 14 degrees Celsius (6.8°F) on Tuesday morning.

The weather was the largest difficulty in the rescue efforts, local media said, citing a local disaster response expert.

Although the 72 hours after a quake are the most likely time to rescue survivors, that will be shortened by the harsh weather, with trapped victims facing the higher risk, it said.

Some water, electricity, transportation, communications and other infrastructure have been damaged but officials provided no further details.

Power to the quake-hit area was being gradually restored, after the state grid sent 18 emergency repair teams, CCTV said. At noon local time, about 88% of the power supply had been restored in Jishishan.

Sstate media footage showed fire rescue personnel combing through rubble of collapsed buildings.

Photos from Xinhua showed a crumbled brick hut in a village some 150 km away, and parts of a two-storey building wrecked.

Tremors were felt as far as 1,000 km away in central Henan province, where local media outlets shared videos of furniture swaying in people's homes.

Tents are set up for people evacuated after an earthquake in Dahejia, Jishishan County, China, on Tuesday. AFP

Woken up by the quake, residents left their buildings and drove out to open areas for safety, local media outlet Jimu reported, showing a photo of people huddled in thick blankets outdoors.

At a university in Gansu's capital, Lanzhou, some 180 km away from the epicentre, students dressed in down jackets were seen lingering in groups outside their dormitory after the quake, a video posted by state-backed The Paper showed.

A major hydropower dam 50km from the epicentre was unaffected by the quake. CCTV reported that the dam, on the upper Yellow River, was operating normally.

Preliminary analysis shows that the quake was a thrust-type rupture, one of three above magnitude 6 to have struck within 200km of the epicentre since 1900, CCTV said. The state media reported at least 32 aftershocks in the hour after the quake hit.

Gansu officials told reporters that the last strong quake of at least magnitude 5.0 to hit within 100 km of the epicentre was in 2019.

A total of nine aftershocks at magnitude 3.0 and above were recorded by Tuesday morning, two of which were at least 4.0 in magnitude, CENC said.

Three thousand kilometres from Jishishan, another earthquake struck at 9:46 a.m. local time (0146 GMT) Tuesday in the Xinjiang region, at a magnitude of about 5.5 and a depth of 10km in the city of Artux, CENC said.

Reuters