A man is in custody after someone was stabbed in Regent Park overnight.Toronto police say they were called to the area of Dundas Street East and Sumach Street just before 11:30 p.m. Saturday for reports someone was running around with a knife.Investigators say the man approached someone else and allegedly stabbed them. That person was taken to the hospital with serious but non-life threatening injuries.The man was arrested at the scene.No further details were immediately available.