Authorities in Nepal on Sunday warned of possible fresh flooding as residents grapple with the devastation caused by recent floods that have killed hundreds of people and left thousands missing.

The warning followed an increase in the Bhotekoshi River’s water level, with authorities advising people in flood-prone areas to stay vigilant.

Notifications were sent to residents’ phones on Sunday as rescue workers evacuated people from a route linking Kathmandu to one of the places most affected by last Wednesday’s floods.

Dharam Raj Uprety, chief executive of Nepal’s National Disaster Risk Reduction and Management Authority, said the warning came as Chinese authorities notified the Nepalese government of increased upstream water flow.

According to Xinhua, China’s water resources ministry said a new lake formed after Wednesday’s flood had largely drained and warned that a crater upstream, with an estimated 1.4 million cubic metres of water, still posed a risk and required monitoring.

Nepal’s disaster agency said on Sunday that 780 have died as a result of the flood, and 2,502 remain missing. On the Chinese side of the border, 16 deaths have been recorded, and 546 people remain missing, according to authorities.

Among the missing are foreigners who were in the region to work or for tourism, with Chinese state media reporting that 261 were unaccounted for in Tibet, including over a hundred Nepalis.

Amid the devastating flood, residents of Galchhi, a municipality in Nepal, sought higher ground on a bridge as rocks were washed down. Houses, cars and farm tractors in the worst-hit communities were covered in thick grey-brown mud.

Mass burials for scores of unidentified bodies commenced on Sunday as authorities began digging graves, particularly in Chitwan and Devghat.

“We had no other choice, so we were forced to take this step,” said Ganesh Aryal, chief district officer of Bharatpur in Chitwan. “We were concerned about the public health risk posed by the rapid decomposition of the bodies.”

Authorities said 96 unidentified bodies in the forest were buried on Saturday. More than 100 others were also scheduled for burial on Sunday.