Tragic day at Fort Hood

I've never been to Fort Hood, but know a lot of people who have and a few who are currently there. Hearing about today's tragedy has really left a sinking feeling in the pit of my stomach.
I've honestly have felt the safest on military bases. There is usually a lot of security and it's not like just anyone can walk on base. Sadly, today's tragedy was caused by soldiers. It's so sad.
I hope my friends who are there are ok. I hope the rumors are avoided and the investigators can determine what would cause someone to do such a horrible thing and why warning signs of this were not seen or acted upon.
My thoughts and prayers are with the victims tonight.