Eight people were killed and hundreds of others, many of them tourists, were feared missing in Nepal on Wednesday after waves of floodwaters crashed through river valleys and destroyed settlements, officials said.

An unknown number of people were unaccounted for, including the staff at four Nepali Police posts and customs officials stationed at one of the country’s land borders with China, according to Abi Narayan Kafle, a spokesman for the Nepal Police. Eight bodies have been found, Mr. Kafle said. Security forces led by the Nepali Army said that 88 people had been rescued.

As many as 384 tourists, including 291 foreigners, have been reported missing in the affected areas, the Nepal Tourism Board said in a statement. They included dozens of visitors from India, a dozen Britons and at least three Americans. Citizens from Australia, the Netherlands, Malaysia and South Africa were also among the missing.