PHILADELPHIA - A 19-year-old man is being sought in connection to a deadly shooting that claimed the life of an 11-year-old boy and injured a 14-year-old who were shot while riding a motorized scooter last week in Oxford Circle, police said.The Philadelphia Police Department on Wednesday named Khalif Cooper Baldwin as the man "responsible for the murder." Authorities obtained an arrest warrant for Cooper Baldwin on Wednesday but did not release a photo of the alleged gunman.Officers from the city's 2nd district were called to the 1500 block of McKinley Street around 6:30 p.m.