Beijing ? A panda cub bit off part of the thumb of an American visitor who was feeding the animal at a reserve in southwest China, state media reported Thursday.

The 50-year-old woman, identified only as Lisa, had registered in the Wolong Giant Panda Protection and Research Center in Sichuan province as a volunteer, according to the official Xinhua News Agency.

She was wearing gloves and feeding the panda bamboo on Tuesday morning when “suddenly, the panda bit into her thumb,” Xinhua said.

“When she cried out, the cub became excited and gripped more tightly,” it said. “Lisa finally managed to wrench herself free.”

About 20 percent of the thumb had been bitten off, Xinhua said.