PHILADELPHIA — Four people were killed and eight others were wounded by gunfire in Philadelphia on Wednesday, including four victims in a quadruple shooting in Mantua. A 20-year-old man was shot multiple times on West Erie Avenue in North Philadelphia at about 2 p.m. and was pronounced dead at the scene, police said. Moments before, police responded to a double homicide in Kensington. A 45-year-old man was shot seven times in the body and died at Temple University Hospital. A 44-year-old man was shot in the head and died at the scene. A fourth person was found dead Wednesday around 8 p.m., whe…