brawl at a california intersection between a lawyer and a retired police officer. aggressive drivers are a growing threat on the roads. in fact, the most recent study from the u.s. department of transportation attributes more than a thousand deaths to road rage, up 170%. let's go for a ride, doctor. psychologist dr. ryan fuller says cars become weapons in the hands of stressed drivers. what's the mindset of someone who's just really angry on the road? >> now they perceive someone cutting them off just gone one step too far. >> reporter: watch this just days ago. a driver on a los angeles highway cut off another driver. threw a can at him, and got out of his car to yell. so what do you do if attacked? dr. fuller says, first, keep your cool. >> you want to take a few deep breaths. slow things down. >> reporter: most importantly he says, don't make eye contact because that can be interpreted as a challenge. >> reporter: sometimes we have seen people get out of the car and start yelling. is that something they should do? >> best thing they can do is