Mob Rule: Are we reverting to the lawless way of an 'eye for an eye'?

For those of you who wish to view the original article:
http://abcnews.go.com/US/off-duty-cops-witnessed-alleged-suv-driver-beating/story?id=20488628

Well, folks. Looks like this is another case of violence. They just keep piling up. And what's surprising is our law enforcement is slacking.

If you have no prior knowledge of the facts behind the article, I will briefly sum it up. A man named Lien was driving--with his wife and infant--in his black Range Rover when it appeared a motorcycle gang was swarming him. One motorcyclist collided in a "fenderbender" with the black SUV and eventually, the car slowed down. Another motorcyclist tried to open the driver's door and Lien shot forward, running over one of the motorcyclists. The motorcycle gang pursued Lien to a crowded street, took him out and beat him up. Two passer-by ran up and acted as shields for Lien and the beatings stopped. Both Lien and the run-over motorcyclist are in the hospital.

Now, in this article, it appears there were cops on the scene, off-duty and undercover. They did not get involved in any way to stop the attack on Lien. I understand that maybe the undercover cop had to maintain his cover, but there were off-duty cops on the scene! They should have tried to do something! Just because they are not actively working does not take away the fact that they are cops! Letting this man get attacked as retribution for their hurt friend is not the right thing to do. This is reverting back to "mob rule" where we lynch citizens for an accident. I don't think Lien was too hasty in trying to escape the situation in which it appears he and his family are in danger.

Think about it: if you were on the road and several bikes are boxing you in, what would your first impression be? It wouldn't just be something to disregard. It's a safety hazard! And why would these people be boxing you in in the first place?

Additionally, aren't cops supposed to preserve the peace and to stop people from mangling others in the streets?

Disregarding my personal bias for a moment, a few unanswered questions arise. What are the bikers' impressions on the affair? What are the off-duty cops' opinions? Was it the motorcyclist who opened the driver's door the one responsible for Lien's mad getaway? The article was definitely biased towards Lien and some of these questions were unanswered as a result.

Is this a sign of poor police-officer conduct to come?