At least eight people were killed and hundreds displaced when a massive mudslide blocked a river and flooded villages in north-eastern Nepal on Saturday. A state of emergency was declared in the Sunkoshi River region, with Deputy Prime Minister Bamdev Gautam telling local media that 700 army and police personnel were deployed to the area to deal with the "grave" situation. Governments from neighboring India and China have assured Nepal of their assistance, dpa quoted Gautam as saying. Houses were buried by the mudflow after an entire hill appears to have slid down into the river, flooding the nearby community. Eight bodies have so far been retrieved. Eighteen people remain missing and 40 others were injured, authorities said. Army and private helicopters were deployed to the affected area, located east of the capital Kathmandu, to rescue trapped residents. The river had been blocked for 12 hours by the nearly 100-metre-high mud wall. The army used explosives to blast away a part of it, local media reported. Authorities said the controlled detonations would help prevent the large-scale destruction that could come if the mud dam were to suddenly burst.