Security firms are watching Twitter to keep sporting events like NCAA's Sweet 16 safe.

Officials are taking their lead from cops, who've long used social media sites to monitor chatter that could tip them off to criminal activity.

But for sporting events, they're watching for the likelihood of fans rushing the field, vandalizing and stealing equipment.

The idea's already been put into practice: As Minnesota Vikings fans were getting ready for the final game at the Metrodome last December, officials noticed social media talk suggesting some people might rush the field and try to steal a piece of history.

So the security firm increased the number of guards that day to maintain calm during the team's win against Detroit.

--Rob Archer