DETROIT (AP) — Authorities in Detroit are releasing more details about three random killings on city streets over roughly two hours. Mayor Mike Duggan says the shooter may have been emboldened Sunday when he didn’t encounter police after the first shooting. The mayor says no one called 911. The shootings began Sunday at 4:45 a.m. Three people were killed over roughly two hours and a fourth person was injured but survived. A 19-year-old is in custody. Police say he may have a mental illness. The man was arrested following a tip from someone who is close to him. The victims included a woman at a bus stop who was planning to move soon to a suburb.