Reality Check

This morning at 4am, I was given my first scary reality check since moving out of the house back in August. I was woken up by a door banging open and a girl and guy yelling at each other. Swear words were used and as I was getting ready to dismiss the incident as a drunken argument between a couple, I heard the girl cry out for help. At this point, I got out of bed and headed towards the door, but before I opened it, I heard the hallway door to the stairs open and close and two voices (one male and one female) asking the girl if she was okay.
The male voice was talking on the phone, relaying what was happening to someone on the other end. I assumed he was speaking to the police, so I decided it was not necessary for me to get involved. I looked out my peephole in the door before heading back to bed and say that the girl who was crying was the girl who lives across the hall from me. I saw her crying hysterically, leaving our hallway, entering the stairwell.
I went back to bed, but immediately felt uneasy. Sure enough, no more than 2 minutes later, I heard more yelling and banging on the floor below mine. I got back out of bed and went to my computer to look for either the number to campus police or to the front desk of our building where residents "night host" each night.
While frantically searching for ANY number to call, the yelling couple had moved outside, where I could hear the girl now crying out for more help.
I forgot about calling the front desk and dialed 911. The noises stopped outside, which made me even more nervous, and I told the emergency responder everything that I knew about the situation and who the girl was and he said that campus police were on their way. As we were ending our conversation, I saw the girl walking towards the front door of our building from the side where they had been fighting. I continued to relay to the man on the phone what I was seeing as the guy began chasing after her across the front pathway.
Just as the guy reached the front door, he stopped, paused, turned away and began calmly walking towards the side of the building again. I thought this was odd... until 2 campus police officers came out of the front doors of our building.
They called him over and long story short, I went back to bed having seen that the police were talking to both the girl and the guy (separately).
Try though I may, I could not fall asleep. I continued to replay the events over and over in my head, I was very upset by the events.
It was the first time I had ever made a 911 phone call, and while I was very proud of myself in how I handled the situation and for doing the right thing and helping, I was (and still am) very unsettled by what happened. It was a definite wake-up call for me. I have always known things like that happened, but nothing had happened that close to home for many, many years. It was my first real-life grown-up situation since leaving home, and my first reaction was to call my mom.