We are very happy that this incident ended without casualty.

英訳に間違いが有れば正してください。

この事件が死傷者なしで終わったことをとても嬉しく思います
We are very happy that this incident ended without casualty.

ヒント
死傷者

答え
casualtiesと複数にする

We are very happy that this incident ended without casualties.