SHANGHAI, May 16 (Xinhua) -Seven workers, who were wounded after a factory wall accidentally collapsed in Shanghai Thursday, have died in hospital, authorities said.

As of 6:10 pm Thursday, 21 people had been pulled out of the debris and rushed to hospital. Of them, seven died after ineffective treatment.

A car is extricated from the factory. (Photos: China Daily)

Two were known to be still trapped in the ruins.

The wall fell at 11:20 am Thursday on Zhaohua Road in Shanghai's Changning District, trapping an unspecified number of people at the site, according to the municipal bureau of emergency management.

Rescuers carried an injured people to an ambulance around 1:53 pm.

The accident occurred when the factory building was being demolished.

The accident is under investigation as rescue efforts continue.

A snapshot from the live stream of Kankanews.com shows that rescue efforts are underway.