According to the local meteorological bureau, Pingjiang was hit by rainstorms between 1 and 7 am on Saturday, which triggered flash floods.

The county government closed the bridge to traffic on Saturday and stationed workers there after it noticed the structure had been damaged.

It blamed some villagers for ignoring orders to stay off the bridge.

There has been a string of bridge accidents in recent years. Last year, two bridges collapsed in two consecutive days.

One person was killed and 22 injured on July 14, when a bridge in Fujian province collapsed. Less than 20 hours later, another bridge in Hangzhou of Zhejiang province partially collapsed.

Authorities blamed overloaded trucks for the collapses.

However, many netizens were not convinced and argued that most of the bridges that had collapsed were built in recent years, while some much older bridges have withstood floods and overloaded vehicles.

The Wuhan Yangtze River Bridge, built in 1958, has been hit by boats more than 10 times, but has remained in good shape and is still in use.

Netizens also cited the Zhaozhou Bridge in Hebei province, a large one-arch stone bridge built between 595 and 605, making it more than 1,400 years old.

Xiao Rucheng, a professor specialized in bridge construction at Tongji University in Shanghai, said that the Zhaozhou Bridge's longevity is due to good-quality construction and the geological conditions of its location.

"For an arch bridge, location is very important. Usually, if the foundation at the two ends of an arch bridge is not solid enough, floods could soften the foundation and lead to collapses," he said, adding that the Pingjiang bridge collapse needs to be thoroughly investigated to determine the cause.