NANJING - Ten people have been hospitalized and four others remain trapped, after a gas leak accident occurred at a steel plant around noon on Thursday in Nanjing, capital of East China's Jiangsu Province, authorities said.

Carbon monoxide leaked from a pipeline into a gas tank at about 11:50 am, when 14 technical workers were performing maintenance work in the gas tank at the Meishan Steel Plant located in the city's Yuhuatai district, said a spokesman with the city's safety supervision bureau.

Rescuers are still trying to rescue the trapped workers from the gas-dense tank, and the conditions of those who have been hospitalized are not yet known.

The cause of the accident is under investigation.