SIOUX FALLS, S.D. (KELO) — Authorities are asking the public for help to locate a 15-year-old who was last seen at 4 p.m. Tuesday near East Heinert Street in Mission.

The Mellette-Todd County Sheriff’s Office said Gage Olsen walked away from a rehab center in Rapid City. He is considered a runaway and was listed in the NCIC register.

Those who see Olsen or know of his whereabouts should call 911 immediately.