At least 21 people have been killed as flash floods and landslides ravaged mountainous areas in northern Vietnam, disaster officials said Friday.

About 37 houses have been destroyed along with more than 1,700 hectares (4,200 acres) of crops, the flood and storm control department said.

In the northwestern province of Lao Cai, nine people -- including a three-year-old boy -- died when flash floods sent rocks and soil crashing into a rural village, official media reported.

Authorities are searching for two other people still missing after the incident in the Sapa region, which is popular with tourists, although no foreigners are believed to have been affected.

More than 260 deaths from floods were reported in Vietnam last year.