A British Airways Boeing 777-236 operating as Flight BA2276 to London Gatwick sustained substantial damage in an accident at McCarran International Airport (KLAS), Las Vegas, Nevada. The flight left the gate at 16:00 and taxied to runway 7L for departure. About 16:12, the captain lined up for takeoff and advanced the engines to takeoff flex power. The captain was the pilot flying (PF) and the first officer (FO) was the pilot monitoring (PM). The relief first officer (RFO) was sitting in the cockpit jumpseat. During the takeoff roll they heard a “bang” or “thud” sound just before the airplane reached 80 knots (kts), and the airplane veered to the left. The captain announced he was stopping, retarded the thrust levers to idle, and began applying wheel brakes. As they were braking, the FO noticed the thrust levers began moving forward, and he disconnected the autothrottle (AT). As the airplane came to a stop the captain noticed the left (No. 1) engine exhaust gas temperature (EGT) indication turned red and the left engine fire indication came on, accompanied by an audible fire bell. The captain set the parking brake and called for the FIRE ENG LEFT checklist, and the FO performed the checklist memory items. As part of the memory items, the FO moved the left fuel control switch to fuel cutoff, pulled the left engine fire switch, and rotated the left fire switch to the stop to discharge the first fire bottle. The second fire bottle was discharged 15 seconds later. The RFO asked the captain if he should make an announcement to the passengers, and the captain approved. The RFO used the public address (PA) system to announce that passengers and cabin crew should remain seated. The RFO then noticed the shadow of a large cloud rising above the shadow of the fuselage, and he asked the captain if he should go into the cabin to investigate. The captain again approved. The RFO left the flight deck and met a cabin crewmember at door 2L, who said she had been trying to call the flight deck. The RFO observed black smoke, an orange glow, and a cabin window glass becoming “crazed.” He told a cabin crewmember to get ready to evacuate and returned to the flight deck. While the RFO was in the cabin assessing the situation, the FO started the Auxiliary Power Unit (APU) in accordance with the follow up reference items on the engine fire checklist. When the RFO returned to the flight deck he reported they needed to get off the airplane immediately. The captain commanded the FO to call the tower, then utilized the PA (public address) system to order an evacuation, and activated the evacuation alarm. The captain stated he attempted to run his portion of the evacuation checklist from memory and he missed the second step of ensuring both engines were turned off. The FO, who was referring to his portion of the QRH evacuation checklist, stated he spent between 15 to 20 seconds attempting to open the outflow valves (OFV) to depressurize the airplane for the evacuation, utilizing their respective switches on the cockpit overhead panel. However, recorded information showed the OFV selection switches remained in the automatic position. According to cockpit voice recorder information, a sound similar to the engine fire switches were pulled about 16:13:20, followed about 2 seconds later by a sound, similar to the fire switch handle, being rotated. The other engine fire bottle was discharged about 3 seconds later, as called for in the evacuation checklist. The RFO noticed the right engine EICAS showed that the right (No. 2) engine was still operating. He pointed this out to the FO, who then moved the right engine fuel control switch to the fuel cutoff position. The FO stated he then also pulled the right engine fire switch. According to data obtained from the flight recorders, the right engine had remained operating for approximately 44 seconds after the captain gave the evacuation command. About the same time as the right engine was shutdown, the forward cargo bay fire warning light illuminated and the fire bell sounded in the cockpit. The captain armed the cargo fire switch and discharged three of the five cargo fire bottles. All of the occupants and crew evacuated the airplane through various exits and slides. During the evacuation at least 2 of the cabin crew received minor and serious injuries. Some passengers had retrieved bags from the overhead lockers after the aircraft stopped and before the evacuation command was given. The flight attendants agreed that carry-on bags that some passengers took while evacuating, were not a problem during the evacuation. PROBABLE CAUSE: “The failure of the left engine high-pressure compressor (HPC) stage 8-10 spool, which caused the main fuel supply line to become detached from the engine main fuel pump and release fuel, resulting in a fire on the left side of the airplane. The HPC stage 8-10 spool failed due to a sustained-peak low-cycle fatigue crack that initiated in the web of the stage 8 disk; the cause of the crack initiation could not be identified by physical inspection and stress and lifing analysis. Contributing to this accident was the lack of inspection procedures for the stage 8 disk web.”