MORRISANIA - Police arrested a Bronx teen on Sunday as part of their Clean Halls program. Authorities say the 19-year-old suspect was stopped outside an apartment complex in Morrisania, where he was found to have a semiautomatic handgun. Authorities were there already on patrol for an active robbery pattern in the 44th Precinct. The initiative allows police to stop anyone on a property whose landlord has granted them permission to do so.