Rescuers had pulled the dead and injured from the silt- covered wreckage of five houses buried under mud in Achham district, about 450 km (281 miles) west of the capital city of Kathmandu, said Dan Bahadur Karki, a police spokesperson, Reuters reported.
Local media footage showed rescuers clearing slush with their hands in a desperate search for the missing people who were believed trapped. Officials said the injured had been rushed to a nearby hospital.
Flash floods and landslides occur frequently in the mountainous terrain of Nepal, especially during annual monsoon rains between June and September.
At least 48 people have been killed and 12 are missing across the country in flash floods and landslides so far this year, according to official data.