At least 16 people were killed and five others injured after a fire ripped through a market in the city of Shenzhen in China's southern Guangdong Province, according to the city's fire department.

The department deployed 29 fire engines, carrying 145 firefighters to put out the blaze early Wednesday morning.

The fire was contained in two hours but engulfed an area of 1,000 square metres, said Wang Long, a security guard who was near the market when the fire broke out.

"At that time I was on patrol and saw dense, black smoke on the sky," said Wang. "The smoke was acrid and we felt uncomfortable after breathing in the smoke."

Cause unknown

The Rongjian Farmers' Market is a wholesale produce market in the Gongming New District of Shenzhen.

The market has more than 500 tenants and is the biggest in the district, according to city officials.

Some of the tenants worked and lived in the stores, a fire department spokesman Xinhua news agency.

The road around the market and surrounding businesses remain closed, as firefighters were still clearing the ember and searching for survivors in the debris.

The cause of the fire is unknown. But a fire department spokesperson said the investigation will continue.

China, the world's second-largest economy, has a poor workplace safety record.

Fire exits in factories, office buildings and shops are often locked or blocked entirely to prevent workers from taking time off or stealing.

Source: Agencies