On 7 December 1944, a powerful earthquake in the Tokai region forced Mitsubishi to halt aircraft production at its plant in Ohimachi, Nagoya. An air raid made by B-29s on the Mitsubishi Engine Works in Daiko-cho, Nagoya a week later caused extensive damage to the works and a severe setback in production. Horikoshi, who had been at a conference in Tokyo with Imperial Navy officers to discuss the new "Reppu" fighter, returned to Nagoya on the 17th, in time to experience another air raid on the Mitsubishi factories the next day. As a result of the air raid, the company evacuated its machinery and engineers to the suburbs of eastern Nagoya. Horikoshi and the Engineering Department were rehoused in a school building which had been requisitioned.