Three highways, including the key Prithvi highway, connecting Kathmandu to the rest of the country have been blocked by landslides, and heavy equipment is being used to try open the routes, said Tiwari.
The government had issued flood warnings across the Himalayan nation warning of massive rainfall.
Buses were banned from traveling at night on highways and cars were discouraged. Security forces were ordered to high alert.
Home Minister Ramesh Lekhak told reporters that officials are still collecting information on the effects of the flooding.
“The government’s priority right now is to rescue the people and help those who have been affected,” Lekhak said.
Parts of Kathmandu were inundated by swollen rivers with many houses flooded and residents forced to move to top floors. A huge area on the southern side of the city was mostly flooded. An army helicopter was used to pick up four people who were unable to leave their houses. Most of Kathmandu was without power and internet for a period of time.
The monsoon season that bring heavy rainfall began in June and usually ends by mid-September.