How did Apollo 1 die?

Apollo 1, originally designated AS-204, was tragically lost in a cabin fire during a pre-launch test on January 27, 1967. The fire broke out due to an electrical fault in the pure oxygen atmosphere inside the command module. Astronauts Gus Grissom, Ed White, and Roger B. Chaffee were unable to escape due to the design of the inward-opening hatch, which was difficult to open quickly. This disaster led to significant changes in NASA's safety protocols and spacecraft design.