POLICE RESPONDING to several calls about a person with a gun shot and killed an unidentified 33-year-old man in North Philadelphia late Thursday night, after he reportedly pointed a gun at them, police said yesterday. Chief Inspector Scott Small said two responding officers from the 25th District, headquartered on Whitaker Avenue near Erie, spotted a man matching the description of the man with the weapon at 10th and Ontario streets shortly after 11:30 p.m. He was carrying a .357 Magnum revolver with a long barrel in his waistband, police said.