Walls of mud barreling down a hill buried 10 college students sleeping in a resort cabin and flash floods submerged the streets and subway stations in Seoul, killing at least 32 people Wednesday in South Korea's heaviest rains this year.

The students were engulfed by a landslide in Chuncheon, about 68 miles (110 kilometers) northeast of Seoul, said fire marshal Byun In-soo. A married couple and a convenience store owner also died.

Witnesses interviewed on television said the landslide sounded like a massive explosion or a freight train. They described people screaming as buildings were carried away by rivers of mud.

About 670 firefighters, soldiers, police and others rushed to rescue those trapped and extract the dead from the mud and wreckage in Chuncheon, where 24 others were injured and several buildings destroyed.

In southern Seoul, 16 people died when mud crashed through homes at the foot of a mountain, the National Emergency Management Agency said. Three others also died after a stream just south of the capital flooded, and 10 people were reported missing throughout the country, the agency said in a statement.

Fast-moving mudwaters filled the streets in Seoul on Wednesday, sending residents scrambling to the roofs of their partially submerged cars.

Water filled some subway stations and spewed from sewers. TV images showed people in one flooded subway station using shovels, brooms and a wooden board in an effort to keep more rain from coming in.

Footage showed officials rescuing hikers stranded on mountainsides. People plodded down streets covered with knee-deep water, many barefoot, their pants rolled up. In Seoul's center, cars were restricted from entering the lower part of a submerged two-level bridge.

The heavy rain since Tuesday left about 620 people homeless and flooded 720 houses and about 100 vehicles throughout South Korea, the emergency management agency said.

About 17 inches (440 millimeters) of rain fell on Seoul and more than 13 inches (340 millimeters) on Chuncheon in the last two days, about 15 times more than the average two-day rainfall at this time of year, according to the state-run Korea Meteorological Administration.

Weather officials said another 10 inches (254 millimeters) could fall in northern South Korea, including Seoul, through Friday.

The Seoul Metropolitan Police Agency issued a traffic emergency, mobilizing more officers to deal with the inclement weather.

Seoul, a bustling capital of 10 million, shut down portions of two major highways stretching along each side of the main Han River because of high water levels, said disaster official Kim Ji-hwan.

A dam located just east of Seoul was discharging 16,400 tons of water per second, said Cha Jun-ho from the Han River Flood Control Office. The dam already discharged about 1,000 tons per second days before the recent downpours.

People in Seoul, where smartphones are ubiquitous, posted dozens of photos on Twitter and Facebook showing inundated streets and mud-covered cars. Many complained online that Seoul had neglected to prepare for the downpours.

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Associated Press writer So Yeon Kwon contributed to this report.