Over five agencies and 100 law enforcement officers responded to fights in South Boston yesterday around 5:30 pm. It took that many to contain a series of gang fights that involved and were witnessed by over 1,000 youths in the Carson Beach area of the city.

The Boston Globe says that the fighting was among rival gang members and that many were drawn to the scene on Monday to watch the violence unfold. Apparently the first fight broke out around 5:30 and police responded to find the beach and parking lots overflowing with kids aged 14-19. State police had to call in tactical ops teams, SWAT teams, and emergency deployment teams to control the situation.

The kids reportedly dispersed, many boarding the train and headed both north and south to continue the fights. Although many peaceful Memorial Day outings were undoubtedly ruined by the fighting, there were no reports of serious injuries as of yesterday. The police are still investigating the actual gang ties behind the fights and there’s no official word on how many of the 1,000+ were actually fighting and how many were just watching.

It looks like social media sites like Facebook and Twitter played a part in the fights, which mirror incidents that had been happening over the course of the entire weekend.

Police said the gang members are part of a group of more than 1,000 youths who have used social media sites like Facebook to plan unruly gatherings on the beach on three of the past four nights. The beach falls under the jurisdiction of the State Police, who have been unable to prevent the violence.

The report doesn’t detail any specific Facebook pages that served as hubs for the planning, and a search of the social media site yields no centralized page or groups. It’s most likely that the teens used messaging and status updates to organize the gatherings at the beach.

Twitter has blown up about the violence, as Carson Beach was trending up until just recently. It’s hard to say that specific tweets involving Carson Beach were organizational tweets, directing people to the site of the brawls. But around 15 or so hours ago – around the time of the first fights being reported – there are a bunch of tweets that simply say things like “otw Carson Beach” and “Carson Beach, abt to roll up.”

People also noticed some disturbance in the area and reported on Twitter:

The reaction today is mixed between those simply shocked by the report that such a large number of youths were involved, and those that dispute those reports:

Whether or not a thousand kids were actually involved or that number is hyperbole, police say that was the largest gathering of teens at the beach in the last twenty years. If Facebook and Twitter played a significant role in the organization of these gatherings, it just shows the power the social networking sites have to get people moving behind a cause – whether that cause is for good or for violence.