Beijing —

Already harrowing rescue efforts along the China-Nepal border are being complicated by the risk of new flooding or landslides, with authorities in China and Nepal pausing rescue efforts Friday due to those fears.

A barrier lake – holding enough water to fill an estimated 1,000 Olympic swimming pools – began overflowing on the China-Nepal border, where it formed after a powerful landslide and torrential flooding devastated the area on Wednesday. A barrier lake is a body of water created by debris damming up a river.

Helicopter rescue operations in Nepal’s flood-hit Rasuwa district were stopped and locals were seen rushing up a hill after reports that the lake had begun to overflow, the Reuters news agency reported, citing a witness.

Chinese state broadcaster CCTV reported late Friday morning the newly formed lake has begun overflowing non-stop, posing such a great risk that rescue teams cannot proceed to the hard-hit land port.