Gu Gu

The 15-year-old had jumped over a 4-foot, 7-inch barrier surrounding an outdoor exercise area for pandas on Monday afternoon while 8-year-old Gu Gu and another bear were being fed.

The teen startled 240-pound Gu Gu, who bit the unwanted visitor on both legs, said Zhang, the director of the zoo management office.

The Beijing News identified the teen as Li Xitao, citing emergency medical officials who said he was so viciously attacked that his bones were showing. Chunks of flesh were left behind in the ambulance, they said.

Gu Gu was in the news last year when he was bitten by a drunk tourist. The man jumped into the bear's pen and tried to hug him, but was bitten instead. The tourist retaliated by biting the bear in the back.

The panda enclosure operated normally after the attack, the official said. Gu Gu was seen snacking on bamboo later in the afternoon, The Beijing News said.