One person is in custody after someone was stabbed inside a building in Regent Park.Toronto police say they were called to an apartment building in the Sackville Street and Dundas Street East area just before 7:30 p.m. Saturday. When they arrived they found a person suffering from a stab wound.The victim was taken to a trauma centre in serious condition.Police say a suspect was arrested at the scene and they were also taken to hospital with unknown injuries.Investigators did not elaborate on the circumstances that led up to the stabbing.