Sports rivalries intensify, turn violent

>>> all he wanted to do was watch a baseball game. but a father two of ended up in a coma beaten by two men at dodger stadium in los angeles . while it's believed to be an isolated incident, the attack has led to sweeping security changes. and as many across the country wondering if they are safe in the stands. nbc's miguel almaguer reports.

>> reporter: in san francisco --

>> as we keep brian in our thoughts.

>> reporter: a moment of silence for giants fan brian stowe , the 42-year-old father two of is fighting for his life in a los angeles hospital. while leaving opening day at dodger stadium , stowe was attacked.

>> i heard someone yell some cuss words and then we see brian on the ground. flrt the parking lot , two unidentified men nearly beat him to death. likely, police say, because he was wearing a giants jersey on the turf of their arch rival.

>> they are being taunted from when they walked out of the stadium.

>> reporter: a paramedic, tonight brian stowe remains in a coma.

>> the attack at dodger stadium is one of the most savage incidents to ever happen here. but it's certainly not the only violent one as a pro sporting event .

>> unbelievable. where is the security?

>> there's the infamous basket brawl . indiana players attack detroit fans.

>> you got to be kidding me.

>> while in chicago, fans attack a kansas city coach. from brawls in the bleachers to fistfights in the stands, even a tennis match has resembled what you would expect in a boxing ring .

>> it's not just the dodgers. it's soccer. it's hockey. it's basketball. you know, we are experiencing a degradation of behavior.

>> reporter: today in boston, long time columnist dan shaughnessy is covering one of the biggest rivalries in professional sports .

>> you always see stuff in the sfand red sox are playing the yankees. whenever you have that mix, it's always combustible. people drinking. red sox /yankee fans going at each other.

>> reporter: back in los angeles , sweeping change is under way.

>> on our way home, instead of talking about the game, we're talking about what we saw in the stands and the parking lot . and it's sick.

>> reporter: the sea of dodger blue will see an increased presence of lapd blue. the former l.a. police chief has been hired to overall stadium security, which will include license plate scanners, observation towers, increased lighting and undercover operations. more focus on security off the field so fans can enjoy what's happening on it. miguel almaguer, nbc news, los angeles .