Authorities fear a second landslide and a disease outbreak are looming at the scene of Papua New Guinea’s mass-casualty disaster because of water streams and bodies trapped beneath the tons of debris that swept over a village, a United Nations official said Tuesday.

A mass of boulders, earth and splintered trees devastated Yambali in the South Pacific nation’s remote highlands when a limestone mountainside sheared away Friday. The blanket of debris has become more unstable with recent rain and streams trapped between the ground and rubble, said Serhan Aktoprak, chief of the International Organisation for Migration’s mission in Papua New Guinea.