Rescue workers strained to plow through eight-foot piles of frozen sludge, which blocked the entrances to destroyed villages. Emergency vehicles struggled to navigate icy, damaged mountain roads. Victims with serious injuries were rushed to hospitals in cities, as demand for medical care overwhelmed the villages’ limited capacities.

In the wake of China’s deadliest earthquake in nearly a decade, emergency workers raced to find survivors and distribute aid in Jishishan County in China’s northwest. They were running up against the challenges of rescue work in bitter cold in a remote part of Gansu, one of China’s poorest provinces.

The quake, which hit late Monday night, killed at least 131 people, most in Gansu but some in neighboring Qinghai Province, according to official tallies updated on Wednesday. The death toll had risen from 120 the day before, and the window for rescuing survivors — shorter than usual due to the freezing conditions, experts said — had narrowed.

More than 87,000 people had been temporarily resettled as of Wednesday morning, Gansu officials said at a news conference. Photos in state media showed rows of blue tents erected at three main resettlement sites across the county, where residents wrapped in thick coats huddled around vehicles equipped with power outlets to charge their phones, or lined up for bowls of hot food. Others lit bonfires in the street to keep warm.

When the quake struck, according to state media, temperatures in Jishishan, a rural and mountainous cluster of towns and villages home to about a quarter of a million people, were at nearly -20 degrees Celsius, or -4 degrees Fahrenheit, part of a cold spell that has gripped much of China. The quake had a magnitude of 5.9, according to the United States Geological Survey, though the China Earthquake Administration put it at 6.2.