Jennifer Graves-Smith was found in the lobby of an apartment building in Halifax early Wednesday. (Halifax Regional Police)

An 18-year-old with autism is safe after she disappeared for nearly 10 hours in bitter cold.

Jennifer Graves-Smith vanished after leaving her school, Halifax West High, at about 3:30 p.m. AT on Tuesday. She was reported missing when she failed to turn up for her bus ride home.

Halifax Regional Police said the teen wandered near the school for hours and ended up in the lobby of a nearby apartment building just after 1 a.m. Wednesday.

"We determined she was wandering around and she just kind of hid in the lobby area," said Staff Sgt. Darrell Gaudet.

The teen was unhurt, Gaudet said, and was reunited with her family after an assessment by paramedics.

Police launched the search for Graves-Smith as temperatures dipped to –20 C Tuesday.

Teen usually reliable

Police said it was unusual for the teen to disappear as she did. Though she had missed the bus before, she would normally return home a short time later.

Police were also worried because Graves-Smith usually turns away from people who approach her.

Flyers with the teen's photo were distributed in the Clayton Park and Bayers Lake communities.

Police called in ground search-and-rescue crews to help after someone spotted the teen walking on a wooded path toward Keshen Goodman Public Library on Lacewood Drive.

With files from The Canadian Press