WICHITA, Kan. (AP) — Police are conducting a search along railroad tracks and a wooded area near Derby for a 4-month-old boy who was last seen with his father.

The search began Monday near 55th Street South and K-15, Wichita police confirmed. The Wichita Eagle reports that K-9 units along with the Sedgwick County Sheriff’s Department were called in to support the search.

Police say Vincent Moore’s mother reported him missing last Thursday. She told police the boy and a 2-year-old child were with their father for visitation beginning June 5. She said the father did not return the children and took them to Texas before returning to Wichita.

The father was arrested Wednesday on unrelated warrants. The 2-year-old was with him but Vincent was not.