In real life, an ambulance comes to a woman's house to take her to the hospital, hopefully to save her life. On the way to the hospital the ambulance is hit by a semi truck and everyone on board the ambulance is killed.

The passage is an example of situational irony. Situational irony is a type of irony (and a type of figurative language). Meaning a contrast between what is expected and what happens. The question's situation ends up in a different way than what is generally anticipated. In situational irony, both the characters and the audience are fully unaware of the implications of the real situation.