KATHMANDU, Oct. 15 -- A wall of mud 20 to 25 meters high swept through a hydropower camp at Salleri, in northern Gorkha district, at about 6:30 a.m. on Sunday. By Tuesday night the people it had not reached were still being flown out by Nepal Army helicopters, and six were unaccounted for.

The numbers have moved quickly. The United Nations said on Monday that authorities counted at least five people missing and 95 rescued. In its third situation report, issued at 10 p.m. on Tuesday, Nepal's National Disaster Risk Reduction and Management Authority counted 508 rescued, 457 Nepali nationals and 51 foreigners, and six missing, four men and two women. The report does not give a death toll.

The cause has been revised too. Early accounts, inc...