There's a knife on this train - adventures in city living

I was taking the T home after a busy day at work. I was hungry and tired and still had many stops to go before I made it home. I'm listening to my ipod when I start to hear shouting over the music. I look to my left and see an older man clearly angry about something. I pause my music and hear this older guy yelling at an even older guy. "Fuck you I was in Afghanistan and Iraq! I will fucking stab you, I have a knife." (I highly doubt he was in both Afghanistan and Iraq. I think he's a bit too old for that.) And he did have a knife and not just some tiny pocket knife, he pulled out a rather large folding knife.

The guy he's threatening says something back to him that I can't hear but I can tell that whatever he says pisses off the guy with the knife. "Fuck America, fuck all of you!" A younger guy tries to calm the situation down but the knife is still out. The train stops, the doors open and the guy with the knife gets off the train.

At this point I'm not really sure what to do.  Do I call the police? Alert the T driver? While I'm thinking this over our train is suddenly surrounded by Boston PD. This was within a minute of the guy jumping of the train. The T driver let's us know that we won't be moving for a few minutes. Everyone pulls out their phones and starts tweeting, texting and updating facebook. After a couple of minutes the T driver makes another announcement "sorry about the crazy person". Why thank you for the apology.

The police finally realize that the guy has left the train so we are let go. As the train starts to roll away we see a cluster of police cars up ahead. There's a guy in the middle of about 6 cops, they caught him, the train cheers.

Sometimes you just get a vibe from someone and we all got this vibe. This guy just looked crazy. From what I gather the guy he flipped out on bumped into him. It's the B train at rush hours. If someone doesn't bump into you I'd be shocked. In all my years of taking the T I've never actually seen anyone pull a weapon. I have had my butt groped and a guy threaten to rip my head off for looking at him (fun fact, I hadn't even glanced at the guy) but never a weapon.

Living in the city is always an adventure. I probably won't tell my mother because she worries about my city living life which is funny because she grew up in a rough part of Boston and told me all these stories about how she took care of herself. I think she still thinks that Boston is how it was in the 60s and 70s which was a lot worse than it is now.