exercise in the tunnel a month before. The train crew were persuaded to return to the train, where they uncoupled the three tankers still on the rails and used the locomotive to drive them out. Greater Manchester fire brigade then loaded firefighting equipment onto track trolleys and sent a crew with breathing apparatus (BA) in to begin their firefighting operation at the south end of the train. They also lowered hose lines down one of the ventilation shafts to provide a water supply. At the same time, crews from West Yorkshire fire brigade entered the tunnel and began fighting fires in the ballast at the north end of the train. However, at 9.40 a.m., the pressure in one of the heated tankers rose high enough to open its pressure relief valves. The vented vapour caught fire and blew flames onto the tunnel wall. The wall deflected the flames both ways along the tunnel, and the bricks in the tunnel wall began to spall and melt in the flames. The BA crews from both brigades decided to evacuate. They managed to leave just before the first explosion rocked the tunnel. The firefighters were saved because blast relief shafts 8 and 9 acted as flame vents (a function their designer never envisaged). Left to itself, the fire burned as hot as it could. As the walls warmed up and the air temperature in the tunnel rose, all 10 tankers discharged petrol vapour from their pressure relief valves. Two tankers melted (at approximately ) and discharged their remaining loads. The fuel supply to the fire was so rich that some of the combustibles were unable to find oxygen inside the tunnel with which to burn; they were instead ejected from vent shafts 8 and 9 as fuel-rich gases that burst into flame when they encountered oxygen in the air outside. At the height of the fire, pillars of flame approximately high rose from the shaft outlets on the hillside above. The gases are estimated to have flowed up these shafts at . Air at this speed is capable of blowing around heavy items: hot projectiles made from tunnel lining (rather like lava bombs from a volcano) were cast out over the hillside. These set much of the vegetation on fire, and caused the closure of the A6033 road. In the cleanup operation afterwards, small globules of metal were found on the ground surrounding