We join the story at the point where the first car accident has happened.
Thus, the outcome has taken place.
You’d recollect that paramedics reached the scene quickly and provided prompt, appropriate treatment. This was followed up by those in the hospital, too.
They were all trying to prevent further damage/ complications.
[At this stage, the accident had already occurred, so that couldn’t be prevented anymore.]
These measures constitute secondary prevention: prevention of further damage/ complications after the “outcome”/ condition has already occurred.