Fire
noun
Fire is a thing that makes more fire. Basically fire is fire.
かじ
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
火事があった場所は、アパートの五かいです。
The fire was on the fifth floor of the apartment.
何か臭うんだけど。もしかして、火事じゃない？
I smell something strange! Maybe a fire?
昨日、家が火事になる夢を見たんです。
Yesterday I had a dream that my house caught on fire.