CHANGSHA -- Seventeen people have been hospitalized after eating beef sold by an unlicensed butcher in central China's Hunan province Thursday, the local government said Friday.

As of Friday night, the patients were still under observation, but none of the cases were critical, the government of Tianyuan district in the city of Zhuzhou said in a press release.

It said the patients, all residents of the same community in Tianyuan, bought the beef from a local resident surnamed Yi on Thursday.

Yi had butchered cattle and sold the beef in the community without authorization.

"Neither the cattle nor the beef underwent quarantine checks," the document said. "Nor was the seller authorized by market regulators to sell the beef."

The residents felt nauseous after eating the beef and sought treatment between Thursday night and Friday morning, it said.

Health authorities have ruled out the possibility of animal-borne diseases through lab tests of the beef.

Local health, food safety and market regulation authorities have launched a joint investigation into the incident. Yi has been detained for questioning.

Meat is strictly quarantined in Chinese cities and only products from licensed butchers are allowed to be sold.