First, the blow-by-blow is on Twitter: http://twitter.com/spinuzzi
Two students and I camped out in our computer classroom, which is a converted bomb shelter. We felt perfectly safe and kept up to date via Twitter, Facebook, and text messaging. Among other things, I communicated with other professors and admin staff in lockdown along the hall.
At one point, a SWAT team showed up, touched base with us, and asked us to remain there until we got the all-clear.
We were in Parlin, and we received updates from social media suggesting that a second shooter was barricaded in Calhoun, the building immediately south of us. However, we saw no shooter.
Honestly, the situation was quite surreal. The classroom has only one window, in the door. The door's about three inches thick. So we felt completely safe. At the same time, we watched an update that a San Antonio TV station had put on the web. The students had okay mobile phone coverage; my phone wouldn't call out, but the classroom had a corded phone so I was able to call loved ones.
Around 11:40, they surrounded the all-clear, and we went home.