Rescuers search for victims and survivors at the scene of a fatal bus accident that occurred early this morning in Xiapu county of Ningde city, East China's Fujian province, June 20, 2012. [Photo/Xinhua]

FUZHOU - A long-distance bus plunged into a ravine in East China's Fujian province early Wednesday, killing at least 17 people and severely injuring three others, local authorities said.

The accident took place on a viaduct in a section of an expressway in the county of Xiapu in Ningde city at about 2 am when the bus overturned and fell more than 50 meters into the ravine, said Yang Peiqin, secretary of the Xiapu County Committee of the Communist Party of China.

The bus was travelling from eastern Chinese city of Wuxi in Jiangsu province to Fujian's Xiamen city with altogether 45 people aboard when the plunge happened. The injured people have been rushed to hospital, Yang said.

It was not immediately known whether all the other people aboard the bus have been pulled out of the vehicle. Local police, firemen, border troops, expressway and medical authorities have launched a rescue operation.

An investigation into the cause of the accident has been underway, Yang said.

Xinhua reporters are en route to the scene.