[Via CNN-TV]

Police got tipped off by one of the victims who was shot and was able to call 911. She pretended to be dead and waited for the gunman to leave the area before hiding under desk and made the call.

The shooter (and the police have very good reason to believe it was a lonely shooter), entered the building, shot the receptionist and proceeded to kill 12 other people before allegedly turning the gun on himself. 37 people survived, 5 wounded (among them 4 in critical condition).

The people who survived did so because they barricaded themselves --they were instructed to do so by the SWAT team via cell phones.

It took 3 hours to diffuse the whole situation.

The Chief of Police will not confirm the identity of the shooter nor whether there was only one shooter involved.