Authorities are offering a $6,000 reward for information leading to a 15-year-old Columbia girl who has been missing for a week.

Richland County Sheriff Leon Lott says a person who wanted to remain anonymous donated $2,500 to the reward fund and his department matched it, along with $1,000 from Crimestoppers.

Lott says state and federal agents are helping his deputies look for Gabrielle Swainson. The girl's mother says she last saw her daughter asleep in her bed early in the morning on Aug. 18 when she went to work. When the mother returned, the teen was missing.

The teen's friends and family have spent the past several days passing out flyers with her picture.

Swainson's mother says none of her daughter's clothes or her purse were missing from her home.