Residents of Bihar state in India braced for massive flooding as Nepalese officials prepared to clear a landslide that has blocked the Kosi river. Some 50,000 of the 425,000 people living in the area had been evacuated by Sunday evening from the Supaul, Madhepura, Saharsa, Araria, Purnea, Madhubani, Khagaria, Darbhanga and Bhagalpur districts, threatened by a river blockage that formed following a landslide Friday that killed nine people.

The landslide created a lake 360 feet deep in the river, flooding two hydropower stations and inundating the highway that connects Nepal to Tibet in China. Clearing the blockage could send a 10-foot wall of water sweeping downstream, Press Trust of India reported.

The Calcutta Telegraph reported Nepalese officials are planning to blast away the blockage, sending the water sweeping down into Bihar within 14 hours. Government troops have been given permission to use force to get people out of the danger zone, the Telegraph said.

"We flew along the upstream of river Kosi, from Naugachhia in Bhagalpur district up to Birpur barrage in Supaul district. Everything is quiet, but it may not be the same after the debris is blasted," Bihar government disaster management principal secretary Vyasji said following an aerial survey of the area, the Times of India reported.

The Nepalese government sought technical help from Indian experts. Vyasji said efforts are being made to control the speed with which the water is released.

"After the blasts, water will gush through with a great force and is expected to reach the Birpur barrage in 17 hours thereafter. Then, the next 72 hours will be highly crucial for the rescue and relief operations, both on the India and Nepal sides," Vyasji said.

S.S. Guleria, deputy inspector general at the National Disaster Response Force, said 117 relief camps had been set up for evacuees, reports said.

This is not the first time the river has posed a danger. In 2008, a breach in the embankment at Kushaha, Nepal, produced disastrous flooding in Bihar. The river changed course killing hundreds of people and destroying crops.