A B777 AFTER PUSHBACK THE TUG STARTED TOWING THE ACFT FORWARD ON THE TXWY. THE TOW BAR SHEAR BOLTS SNAPPED ALLOWING THE ACFT TO ROLL FORWARD STRIKING THE TUG.

Narrative

PUSHBACK OF THE ACFT WAS BEING CONDUCTED IN A NORMAL MANNER AND BOTH ENGS WERE STARTED AND AT IDLE. I HAD NOT RECEIVED A 'SET BRAKES' COMMAND FROM THE PUSH CREW. THE BACKWARD MOVEMENT OF THE ACFT HAD STOPPED AND SLIGHT FORWARD MOVEMENT BEGAN WHEN A SUDDEN VIBRATION AND JOSTLING OF THE ACFT OCCURRED. IMMEDIATELY THEREAFTER; THE ACFT CAME TO AN ABRUPT HALT. I IMMEDIATELY INQUIRED OF THE GND CREW WHAT WAS HAPPENING; BUT RECEIVED NO RESPONSE. WITHIN MOMENTS ONE OF MY FO'S WHO WAS MONITORING OTHER FREQS ADVISED ME THAT WE WERE INSTRUCTED TO SHUT DOWN ENGS; WHICH WE DID IMMEDIATELY. SUBSEQUENTLY; A PERSON CAME ON THE INTERPHONE AND INFORMED ME THE TOW BAR HAD BROKEN AND THE TUG WAS WEDGED UP AGAINST THE MAIN GEAR. HE SAID THE TUG DRIVER WAS QUITE SHAKEN UP AND WAS TAKEN OFF IN AN AMBULANCE. HE ALSO INFORMED ME HE DID NOT BELIEVE THE TUG DRIVER HAD SUSTAINED ANY PHYSICAL INJURIES. AT NO TIME DURING THIS EVENT WERE THE ENGS ABOVE IDLE. MAINT SUBSEQUENTLY EXTRACTED THE TUG FROM ITS POS AGAINST THE GEAR AND WE WERE TOWED TO THE GATE FOR REPAIRS. LATER; THE CHIEF PURSER INFORMED ME A FLT ATTENDANT HAD INJURED HER WRIST DURING THE INCIDENT. THE LCL INFLT REPRESENTATIVE TOLD ME THAT LCL MEDICAL PEOPLE HAD LOOKED AFTER THE INJURED FLT ATTENDANT AND IT WAS RECOMMENDED SHE DEADHEAD HOME; WHICH SHE DID.