SAN FRANCISCO -- A severely autistic 16-year-old girl who had been missing for two days has been found badly beaten in San Francisco, her mother said Thursday.

Shyanne White was found on a bus in San Francisco about 8 p.m. Thursday, said her mother, Shandra Pullar, who was headed to the Bay Area from her home in Washington after the news that police have found her daughter. The teen has the mental capacity of a 7-year-old.

It was not immediately clear who spotted the teen and called police or if any suspects had been identified.

An Oakland police detective was en route to San Francisco late Thursday to pick up the teen and take her to a hospital, her mother said.

The teen walked off about 7 p.m. Tuesday from the Fred Finch Youth Center at 3800 Coolidge Avenue in East Oakland.

Her father, Jesse White, who lives in Southern California, said his daughter has severe behavioral problems because of the developmental disability and had been at the center for about six months.

Center CEO Thomas Alexander said youth are allowed to leave the center and doors are not locked. When the teen walked out Tuesday night, she was followed by a staff member on foot and one in a car to International Boulevard and 34th Avenue near the Fruitvale BART station. They lost sight of her there, police said.

It was not clear why staff members did not restrain or stop the teen when they were following her, and Alexander did not return a call for comment late Thursday.

Police on Wednesday night put out an alert about a missing juvenile at risk, and her picture and story was featured online and on television news broadcasts.

Anyone with information about the case should call Oakland Police Department Family Youth Service Division at 510-238-3641.

Reach Kristin J. Bender at kbender@bayareanewsgroup.com. Follow her at Twitter.com/kjbender.