A fire or conflagration (an accidental or uncontrolled blaze, e.g., in a building or forest).
昨夜、近所で大きな火事があった。
There was a large fire in the neighborhood last night.
火事が起きたら119番に電話してください。
If a fire breaks out, call 119.
火事の後、家はほとんど焼けてしまった。
After the fire, the house was almost completely burned down.