HEFEI -- Twenty-three students from a college in Fuyang, East China's Anhui Province, grew ill after dining at a local restaurant Saturday, local authorities said Sunday.

By Sunday morning, one of them was still receiving treatment, and the others had been discharged from hospital, said a spokesman with the Fuyang city government.

The students, all from Fuyang Normal College, showed symptoms of cyanosis, nausea and vomiting after having lunch at a restaurant near the college in Yingzhou district, the spokesman said.

The restaurant has been closed and the owner is in police custody, according to the spokesman.

An initial investigation found that pickles sold by the restaurant contained nitrite, an ingredient commonly used in pickling that can be fatal in excessive amounts.