BEIJING – Blocked mountain roads were hampering rescue efforts after twin earthquakes struck southwestern China and killed at least 80 people, leaving officials worried today that the death toll could rise further.

More than 100,000 residents were evacuated after Friday’s quakes toppled thousands of houses and sent boulders cascading across roads in a remote mountainous area along the borders of Guizhou and Yunnan provinces.

The damage was preventing rescuers from reaching outlying towns, and communications were disrupted after the midday quakes hit in a region of small farms and mines where some of China’s poorest people live. Weather forecasts today said there was a chance of rain over the next three days, which could hamper rescue work.

But there was some good news, with state television reporting that four babies had been born in temporary hospitals set up since the quakes hit.

The first magnitude-5.6 quake struck just before 11:30 a.m. Friday and was followed by an equally strong quake shortly after noon, joined by dozens of aftershocks. Though of moderate strength, the quakes were shallow, which often causes more damage.

The state-run Xinhua News Agency said today that 80 people had died in the quakes. It said earlier that hundreds had been hurt, but did not immediately give a new injury toll today.

Hardest hit was Yiliang County, where all but one of the deaths occurred, according to the Yunnan provincial government’s official website. Another 730 people in the area were injured, Xinhua said. Yiliang’s high population density, flimsy building construction and landslide-prone hillsides were blamed for the relatively high death toll.

Though quakes occur in the area frequently, buildings in rural areas and China’s fast-growing smaller cities and towns are often constructed poorly. A magnitude-7.9 quake that hit Sichuan province, just north of Yunnan, in 2008 killed nearly 90,000 people, with many of the deaths blamed on poorly built structures, including schools.

Xinhua quoted Yunnan’s civil affairs department as saying Friday’s quakes destroyed 6,650 houses and damaged 430,000 others. Besides the 100,000 residents already evacuated, another 100,000 were in need of relocation, the department said.

“The hardest part of the rescue will be handling traffic,” Li Fuchun, head of Luozehe township in Yiliang, was quoted as saying by Xinhua. “Roads are blocked and rescuers have to climb mountains to reach hard-hit villages.”