SHENYANG, April 28 (Xinhua) -- Four workers were confirmed dead in a gas leak at a steel plant in Anshan, an industrial city in northeast China's Liaoning Province, on Friday, the local government said Saturday.

The accident occurred at around 0:00 a.m. at Haicheng Iron and Steel Co. Ltd., a private company that produces 500,000 tons of raw iron a year, said an official with the safety inspection bureau in Anshan.

Five workers were on duty and were taking a nap in their office. "Four of them had died when rescuers arrived," he said on condition of anonymity. "The fifth one was out of danger after timely treatment."

The leak occurred on a gas pipe connected to the company's primary blast furnace, and investigation is continuing on Saturday.

Friday's tragedy came nine days after the deadliest accident in the country's steel sector, in which molten metal spewed through a steel plant in Tieling, Liaoning Province, killing 32 workers and injuring another six.