The death toll from a landslide triggered by heavy rains in northern China has risen sharply to at least 21, authorities said on Sunday, with six others missing.

China has faced deadly floods and historic rainfall in recent weeks, with dozens killed in storms in the northern part of the country.

"Twenty-one people were found dead so far, and six others are still missing," the Xi'an emergency management bureau said in an online statement about the landslide Sunday.

State media had put the toll at four earlier Sunday.

A mountain flash flood in the village of Weiziping, south of Xi'an in Shaanxi province, caused a landslide on Friday that swept away two houses and damaged roads, bridges, electricity supply and other infrastructure, national public radio CNR reported earlier.

A hundred soldiers as well as firefighters were mobilized for the relief operations "which are continuing" Sunday, according to CNR.

CNR broadcast images on Weibo showing rescuers clearing rocks and trees from the edge of a river and carrying victims on stretchers.

According to the Xi'an emergency management bureau statement, more than 980 people were mobilized for the rescue effort, using life detectors and search dogs.

The landslide "destroyed" two houses and caused power cuts in 900 homes, it said.

"According to experts, the cause of the disaster is a flash flood mud-rock flow caused by short-term torrential rain," the statement said.

"Up to now, a total of 186 people have been relocated and resettled... 49 communication base stations in the disaster-stricken area have resumed service, and power supplies have been resumed in 855 homes."