B767 FLT CREW RPTED ACFT ROLLED FORWARD AFTER STOPPING AT GATE AT KJFK.

Narrative

B767-200; SFO-JFK. DURING PARKING; SET PARKING BRAKE; CHKED LIGHT ON; BRAKE PRESSURE NORMAL. TURNED OFF SEATBELT SIGN AND STARTED SHUTDOWN FLOWS AFTER FO SHUTDOWN BOTH ENGS. SAW MOVEMENT IN PERIPHERAL VISION AND REALIZED ACFT WAS MOVING. STEPPED ON PEDAL BRAKES TO STOP ACFT. I NOTED THAT PARKING BRAKE HANDLE WAS DOWN IN THE OFF POS. I RESET BRAKES; PARKING BRAKE LIGHT ON; PRESSURE NORMAL. I TOLD PAX WHAT HAD HAPPENED; AND THAT ACFT WOULD BE PUSHED BACK TO JETWAY AND TO PLEASE BE SEATED AGAIN. WE WERE PUSHED BACK; RESET BRAKES. SYS LOOKED/OPERATED NORMALLY. COMPLETED SHUTDOWN CHKLIST. MADE LOGBOOK ENTRY TO CHK BRAKE SYS. NO PAX RPTED INJURY OR FALLS. 2 FLT ATTENDANTS STATED THAT THEY HAD HURT THEIR BACKS IN THE EMER STOP. BOTH WALKED OFF NORMALLY DEPLANING THE ACFT. ACFT HAD ROLLED 23 FT FROM THE INITIAL STOP POINT. NO DAMAGE TO ACFT OR INJURY TO MAINT PERSONNEL. L ENG WAS 4-5 INCHES FROM AFT JETWAY ON FINAL STOP. BOTH PLTS SAW PARKING BRAKE LIGHT ON; ON INITIAL STOP. SYS CHKED OK ON 3 ATTEMPTS TO RECYCLE AND EVALUATE SYS. RESET AND SHUTDOWN WERE NORMAL -- SECOND TIME AROUND.