NANJING - Twenty-eight people remain hospitalized after a sulfur dioxide leak occurred Thursday morning at a chemical plant in East China's Jiangsu province, local authorities said.

Around 10 am Thursday, a small amount of sulfur dioxide was leaked in a chemical plant belonging to Jiangsu SOPO Group Co., Ltd. in Zhenjiang City, according to an investigative report released by the environmental protection bureau of Jianbi county.

The leak lasted for about five minutes, the report said.

Shortly after the spill, dozens of plant employees and local residents began complaining of an "uncomfortable" feeling and were sent to a local hospital.

The 28 patients who remain in the hospital are under observation and are in no imminent danger.

The plant shut down a sulfuric acid production facility linked to the accident.

A further investigation is under way.

Sulfur dioxide is a poisonous gas with a pungent, irritating smell.