KATHMANDU, Nepal - A steel footbridge collapsed yesterday in western Nepal under the weight of hundreds of people on their way to a fair, plunging scores about 100 feet into icy Himalayan waters. At least 15 were killed and more than 100 were missing and feared dead, officials said.

Troops were being rushed to the area to assist with search-and-rescue operations. But with efforts halted by nightfall, hopes were slim of finding more survivors in the fast-flowing mountain river, said Anil Pandey, a top government official in the area.

Authorities believe about 500 people traveling to a village fair were crossing the Bheri River on the 400-foot-long bridge when its support cables snapped under the weight, Pandey said.

"Some of them managed to climb to safety," he said, "some fell on the banks, but the ones who plunged in the river are the ones who are still missing."

Crowds gathered on both sides of the river, trying to save the victims and treating the wounded. Some who had fallen used the bridge's cables to haul themselves up.

By nightfall, rescuers had recovered 15 bodies, while 32 seriously injured were flown to hospitals, said Dipendra Chetri, a police official who helped rescue people in Chunchu, the village where the bridge collapsed.

"It is hard to say how many people are missing," said police officer Purushottam Khatri, "but the best estimate I can say is more than 100 people could be missing."

Authorities feared there could be many more casualties because the river has strong currents and is difficult to swim. Searches would resume at daybreak today, Pandey said.

Chunchu is about 310 miles west of Kathmandu in a rural part of this Himalayan country with few paved roads. The most common way of traveling is by foot or oxcart.