Three hikers have been killed and two others were frostbitten after they traveled along one of the most dangerous hiking routes in northwest China's Shaanxi province and encountered a terrible snowstorm, a regional rescue team was quoted as saying by West China Metropolis Daily.

At least 50 Chinese backpackers from regions including Shanghai and the provinces of Jiangsu, Zhejiang, Qinghai and Yunnan were trying to cross from Aoshan Mountain to the peak of Taibai Mountain in Shaanxi's Qinling Mountains during the May Day holiday, according to the Shaanxi Shuguang Emergency Rescue Association.

Hiking in the mountains is becoming increasingly popular in China, but many people have insufficient knowledge about the sport, and its dangers.

"The 120-km hiking trail from Aoshan Mountain to Taibai Mountain takes about seven days to walk along, and it covers depopulated zones," said Chen Xutong, a director at the Shuguang association.

"Because the missing backpackers do not have GPS, it is really difficult to find them," he told China Daily.

Chen said that the association's rescue efforts started at about 9 am on Friday, when the snowstorm abated. The 20-person rescue team from the association was searching around the Paomaliang area where the mercury stood below - 10 C. Two of the three victims died from hypothermia, according to West China Metropolis Daily.

By early Friday afternoon, one hiker from Shanghai and another seven from Changshu, Jiangsu province, had contacted loved ones. Thirteen people from Yiwu, Zhejiang province, and three people from Yunnan province have been confirmed safe.

"The extreme weather and low temperature pose the biggest threat," Chen said. The mercury drops 6 C for every 1,000-meter increase in altitude.

He also said the rescuers were trained with medical knowledge.

Meanwhile, personnel at Taibai county were organizing separate rescue efforts.

According to a news release from the county's publicity department on Friday, the regional public security bureau received four reports on Thursday, claiming eight people went missing during the hike.

More than 50 rescuers from the county, divided into three groups, headed from different areas on Thursday afternoon for the mountains.

All the missing people were successfully reached by 6 pm, according to Huang Ma, who told West China Metropolis Daily that there were about 30 to 40 people in total, including a third one who died and two who suffered frostbite.

Cheng Si in Shanghai and Huo Yan in Xi'an contributed to this story.