Heavy rains triggered landslides and flash floods killing at least 11 people in the last 36 hours in Nepal and blocking key highways and roads, officials said on Sunday.

Eight people were missing, either washed away by floods or buried in landslides, while 12 others were injured and being treated in hospitals, police spokesperson Dan Bahadur Karki said.

“Rescue workers are trying to clear the landslides and open the roads,” Karki told Reuters, adding heavy equipment was being used to clear debris.

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.

“The flow of Koshi is rising and we have asked residents to remain alert about possible floods,” Bed Raj Phuyal, a senior official of Sunsari district where the river flows, told Reuters.

He said at 0900 hours (0315 hours GMT) water flow in Koshi River was 369,000 cusecs per second, more than double its normal flow of 150,000 cusecs.

Cusec is the measurement of the flow of water and one cusec is equal to one cubic foot per second.

Authorities said all 56 sluice gates of the Koshi Barrage had been opened to drain out water compared with about 10-12 during a normal situation.

Authorities said the flows of Narayani, Rapti and Mahakali rivers in the west were also rising.

In hill-ringed Kathmandu, several rivers have overflown their banks, flooded roads and inundated many houses.

Local media showed people wading through waist-deep water or residents using buckets to empty their houses.

At least 50 people across Nepal have died in landslides, floods and lightning strikes since mid-June when annual monsoon rains started.

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.

In the northeastern Indian state of Assam, floods have killed dozens and displaced thousands of people in the past few days.