Eighteen people were killed in separate landslides in the Ilam district in the east bordering India, police spokesperson Binod Ghimire said.

Three people were killed in southern Nepal in lightning strikes, and one person died in floods in Udayapur district, also in east Nepal, he said.

Eleven people were washed away by floods and have been missing since Saturday, authorities said.

“Rescue efforts for them are going on,” Shanti Mahat, a National Disaster Risk Reduction and Management Authority (NDRRMA) spokesperson, told Reuters.

Several highways have been blocked by landslides and washed away by floods, stranding hundreds of passengers, authorities said.

“Domestic flights are largely disrupted, but international flights are operating normally,” Rinji Sherpa, a spokesperson for Kathmandu airport, said.

In southeastern Nepal, the Koshi River, which causes deadly floods in the eastern Indian state of Bihar almost every year, was flowing above the danger level, a district official said.

Dharmendra Kumar Mishra, district governor of Sunsari district, said water flows in the Koshi River were more than double normal.

Mishra said all 56 sluice gates of the Koshi Barrage had been opened to drain out water compared with about 10 to 12 during a normal situation, adding that authorities are “preparing to ban heavy vehicles from its bridge”.

In hill-ringed Kathmandu, several rivers have flooded roads and inundated many houses, cutting the temple-studded capital off from the rest of the country by road.

Hundreds of people die every year in landslides and flash floods that are common in mostly mountainous Nepal during the monsoon season, which normally starts in mid-June and continues through mid-September.

Weather officials say rains are likely to lash the Himalayan nation until Monday, and authorities say they are taking “maximum care and precautions” to help people affected by the disaster.