MANHATTAN - Officials say a gun they believe was used to kill an NYPD officer has been found.

The weapon was discovered at the bottom of the East River Sunday morning.

Part of the FDR Drive was shut down for hours as a result of the discovery.

Officials say they will test the gun to see if it was used to shoot officer Randolph Holder in the head.

Holder and his partner were responding to a call of shots fired during a bicycle robbery Tuesday night when he was shot after a chase with the armed thief.

Police say Tyrone Howard opened fire on the 33-year-old officer during the chase.