Thousands of panic-stricken villagers fled their homes fearing flash floods after an overnight landslide blocked a river in quake-hit Nepal’s mountainous north-west, officials said Sunday.

The landslide, which occurred at around midnight, sent mud and rocks surging into the Kali Gandaki river in Myagdi district, causing water levels to rise by 150 meters (490 feet), local official Yam Bahadur Chokhal said.

“We have evacuated about 100 people from the affected area, people in other villages don’t need immediate rescue but thousands have left on their own,” Chokhal told AFP.

An army helicopter carrying soldiers and geologists has reached the site, according to home ministry spokesman Laxmi Prasad Dhakal. “The chopper has landed and our experts are now assessing the situation to find the best way to open the blockage and drain the two-kilometer-long artificial lake created by the landslide,” Dhakal told AFP.

Fresh, smaller landslides have occurred through the morning and are continuing to send debris into the river, hampering efforts to clear the blockage, according to police and district officials.

The region has witnessed several small landslides in recent days, said local official Trivikram Sharma, based in the district headquarters of Beni, 185 kilometers (115 miles) west of Katmandu.

“After the two quakes, villagers have reported several minor landslides and late last night, they said the hill just came down,” Sharma told AFP.

“We cannot immediately assess the risk of flash floods but people are obviously scared that the artificial dam will burst suddenly and submerge their homes,” Sharma said.

No one was hurt or killed in the landslide, according to officials.

Police have issued an alert for villagers living along the river, which begins near the Nepal-China border and flows into northern India, eventually joining the Ganges.