Shortly after the commencement of the takeoff roll from runway 18L, at about 20 knots, as the engines were close to 40-degree Celsius rated takeoff thrust, there was a loud explosion and then the aircraft vibrated and yawed sharply to the left. The takeoff was rejected immediately, and within a few seconds there was a fire warning on the left engine. The augmenting first officer, who had been sitting in the cockpit jump seat, quickly went to the aircraft cabin and visually confirmed that there was a fire in the left engine. Meanwhile, the captain and the operating first officer carried out the emergency procedures to deal with the fire indication. After use of the second fire bottle, the fire warning ceased, and there was visual confirmation by the augmenting first officer that the fire had been extinguished. The emergency response services personnel confirmed that the fire was extinguished. The passengers deplaned using the normal exits after the aircraft was towed to the terminal. After the aircraft was shut down, it was noted that parts from the high-pressure compressor (HPC) had detached from the engine. CAUSES: “An uncontained failure of the third stage of the 3-9 HPC spool was due to the presence of an oxygen-rich segregate produced in the batch of titanium used to construct the 3-5 stages of the spool. The segregate caused locally degraded resistance to fatigue crack initiation in the dove-tail slot bottom, an area of the spool that is subject to some of the higher design hoop stresses. Contributing to the occurrence were the quality control decisions made at the time of manufacture of the titanium, the inability of existing in-service inspection techniques to detect crack zones, and the intolerance of the spool design for slightly degraded material.”