A toddler who was attacked by a 10-year-old girl in an elevator in Chongqing underwent his first brain surgery on Monday.

The 18-month-old boy, Li Xinyuan, entered the operating room at 8:40 am and left at about 2 pm. He remains in the intensive care unit of Chongqing Medical University Children's Hospital after the surgery.

His father Li Shengzhong said the surgery went well and if there is no post-surgery infection or bleeding, the boy is expected to pass the critical stage within three days.

He said he and his wife are relieved by the apparent success of the surgery, but still concerned for their son's health.

The attack happened in the Changshou district of Chongqing on Nov 25, after the toddler's grandmother accidentally left him in an elevator with the 10-year-old girl, surnamed Li. The girl brutally attacked the boy in the elevator while it was going from the first to the 25th floor, surveillance camera footage showed.

The boy was later found covered in blood outside the residential building.

Police filed no criminal charges against the girl because her young age. She and her mother left the city and moved to the Xinjiang Uygur autonomous region on Dec 2.

The incident triggered great public anger and experts recommended sending the girl to rehabilitation.

Netizens questioned the girl's mental health.

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