Kathmandu: The death toll in the massive flash floods in Nepal rose to 162, leaving many, including security personnel and foreign tourists, missing in one of the country’s worst disasters in recent years, police said on Thursday.

The flash floods on Wednesday wreaked havoc across three districts in Nepal.

Nepal Police on Thursday said that the death toll rose to 162 in the flash flood on the Bhotekoshi River that wreaked havoc across three districts on Wednesday.

The flash floods were caused after an avalanche blocked the flow of the Lhende tributary of the Bhotekoshi and first hit Timure, near Nepal’s border with China at Rasuwagadhi.

Much of the settlement, home to hundreds of people, was swept away before the flood surged downstream. With no rainfall reported in the area, residents had no warning of the disaster and were going about their daily routines when the flood struck.

As the scale of the disaster became apparent, Rajendra Dhungana, chief customs officer in Rasuwa and dozens of others fled into the nearby forest. More than 300 vehicles and trucks waiting at the customs checkpoint were washed away.

A preliminary assessment on Thursday suggested that the flash flood was caused by an ice avalanche upstream blocking a river on the Nepal–China border, Disaster Management authorities were quoted as saying by My Republica.

The assessment suggests that the flood in the Trishuli River was caused by an ice avalanche upstream blocking the Lendhe River. The National Disaster Risk Reduction and Management Authority (NDRRMA) said that a debris-laden flood occurred in the Lendhe River following an ice-rock landslide at the Nepal–China border, about 20 kilometres northeast of Rasuwagadhi.

"The same flood appears to have entered the Trishuli River after passing through Timure,” the authority said, amid various theories and assessments regarding the cause of the flood, which has now become a recurring issue.

Disaster expert Basanta Raj Adhikari also argues that an ice avalanche occurred in the Lendhe River, about 20 kilometres upstream of Rasuwagadhi, blocking the river and causing the flooding, My Republica reported on Thursday.

At least 133 Indians and 37 NRIs are among the nearly 500 persons missing, officials said. At least 50 of the Indians were pilgrims for the Kailash Manasarovar Yatra.

After the flash flood, 81 security forces have remained out of contact. Forty four army personnel, 28 Nepal Police personnel and 9 Armed Police Force people deployed in Rasuwagadhi, Syafrubesi and Betrawati among other places have lost contact with the centre.

Meanwhile, the flood and landslides have obstructed various road sections, including a national highway in nine districts, according to a statement issued by Nepal Police.

In some places, the collection of mud and rocks has blocked the road, while in other places transportation has been halted due to possible risks associated with the flood.

A section of the national highway from Nagdhunga in Kathmandu to Mugling has been completely halted for an indefinite period.

This is the main highway connecting Kathmandu with outside districts. Similarly, transport service has been halted on the Mechi Highway of Ilam district, the BP Highway of Kavre, the Kanti Lokpath of Makwanpur, the national highway of Rasuwa, the national highway of Nuwakot, the Prithvi Highway of Dhading, national highway connecting Chitwan and Jajarkot Dolpa road section in Rukum West.

The flash floods have destroyed nine hydropower projects and an equal number of branches of commercial banks. A preliminary report shows 19 motorable bridges and 40 kilometres of highway have been swept away in the flood, with no accounts of the private and public properties so far, the Kathmandu Post report said.

Based on the scale of those unaccounted for, security officials and disaster experts say Wednesday’s flood may rank among the deadliest in Nepal’s modern history—potentially surpassing every disaster since the 1993 floods in Sarlahi, Rautahat and Makawanpur, which killed 1,400 people and have long stood as the country’s benchmark disaster, it added.