TAIPEI, Taiwan — Chinese authorities say at least 11 people have died and 30 are missing in the partial collapse of a highway bridge in the northwest of the country following heavy storms and flooding. A similar number are missing in the southwest after dozens of houses were destroyed by storms.

The official Xinhua News Agency said five vehicles that fell off the bridge have been recovered after the structure in Shaanxi province crumbled at around 8:40 p.m. local time on Friday. A photo released by Xinhua showed a section of the bridge snapped and folded down at almost a 90-degree angle into the rushing brown water below.

It said rescue operations were still underway Saturday in the province’s Zhashui county, with some 20 cars and 30 people still missing.

In Sichuan province to the southwest, an estimated 30 people were missing and around 40 houses wrecked in flooding and storms, Xinhua reported. It said roads, bridges and communication networks in hardest hit Hanyuan county had been damaged or knocked out and that rescue teams had been working since before dawn to restore communications and transport connections.

As its economy boomed over recent decades, China built a huge network of highways, high-speed railways and airports, most of which have helped fuel further growth.

However, a dramatic decline in that economic expansion, the poor-quality infrastructure, poor safety supervision and a desire to cut corners by industries looking to save money have led to a steady stream of deadly accidents.

China’s western and southwestern provinces are particularly prone to flooding and landslides due to their mountainous landscapes and the powerful rivers that run through them. Mining, tourism and rising urbanization have also disturbed a precarious balance with the natural environment that had been sustained over thousands of years.

Shaanxi is best known as one of the fulcrums of Chinese civilization, from which emerged the first emperor, Qinshi Huangdi, who left the famed terracotta army as his legacy outside the capital Xi’an as part of a vast tomb complex that attracts massive numbers of visitors each year.