BEIJING (AP) — A factory explosion in a port city south of Shanghai on Sunday knocked down nearby residential buildings and sent injured people to hospitals, news reports said. There was no immediate word of possible deaths or how many people were hurt.

The explosion at a factory in Ningbo, one of China's busiest ports, struck a neighborhood along the Yong River at about 8:55 a.m., the official Xinhua News Agency and other outlets reported. No other details of the cause were immediately reported.

The blast "knocked down residential buildings," the website eastday.com said, without giving details.

An unknown number of people were taken to a hospital but details of their injuries were unknown, state-run China National Radio said on its website.

Photos on News.163.com showed an injured woman being carried away on a man's back and what appeared to be the body of man lying in the debris of a collapsed building.

Video on the website Tencent News showed a white cloud of smoke rising above the explosion site.