A section of bridge approach of the No.3 Qiantang River Bridge collapses, leaving a huge hole on it, Hangzhou, East China's Zhejiang Province, July 15, 2011. [Photo/Xinhua]

HANGZHOU - An early Friday cave-in in east China's Hangzhou City left at least a truck driver injured and closed down a pivotal road bridge, police and witnesses said.

The cave-in happened at around 2 am, leaving a 20-meter long, 1-meter wide pit on the right lane of the No.3 Qiantang River Bridge, said a traffic police officer at the scene.

A passing heavy truck loaded with steel plates toppled down the bridge but its driver jumped out before it crashed onto the ground.

The injured driver was sent to a nearby hospital. Police said his condition was not critical.

Investigators said the truck was overloaded, as more than 100 tonnes of steel plates were collected from the scene, though the wreck of the vehicle weighed only 32 tonnes.

A resident who lives near the bridge said he heard two bangs and felt his home was shaking. "I thought it was an earthquake," he said on condition of anonymity.

The cave-in site is only a few hundred meters from the Qiantang River, a major waterway in east China.

A temporary traffic ban has been imposed on the bridge and several other roads linking to the bridge. Altogether 13 bus routes have been diverted.

The No. 3 Qiantang River Bridge opened in 1997 and links Hangzhou's city center with the Xiaoshan International Airport. Authorities said it is off-limits to trucks.