Чистая случайность
Accident
he had a small accident; industrial accidents; a
fatal accident1. Несчастный случай с тяжелыми последствиями для жизни и здоровья;
2. Ранения, гибель в бою или катастрофе
Casualty
automobile casualties are very common on this narrow highway
Происшествия менее серьезного характера, казусы
Mishap
I met with a slight mishap;
'We've had a slight mishap to one of our customers… She seemed to have had a fit in the fitting room' (A. J. Cronin)
Mischance
similar mischances are frequently recorded at wrestlings