I've said it before, and I'll say it again: Paint me the picture.
I'm not going to believe that the guy in the side alley is afraid of the streetgang unless you show his fear. Heartrate, sweating, bloodpressure, etc.
Similarily, simply relaying information about a crash doesn't do much to convey the feeling of 'oh crap' associated with it. Details, details, details. It is very hard to go overboard on them (although it is definitely possible: I've had to fix a couple of paragraphs in my own stuff because the details obstructed the flow of the story).