Authorities call NYC explosion a bombing, say motive unknown

 NEW YORK (AP) — Investigators scrambled Sunday to find out who planted a bomb that rocked a bustling New York City neighborhood, scouring shrapnel, forensic traces and surveillance video for any link to an unexploded pressure-cooker device found just blocks away.
Hours after the Saturday night blast that injured 29 people in Manhattan, there seemed to be more questions than answers. All the injured had been released from the hospital by Sunday afternoon.
“We just know there was