Apparently, the swatter (like hundreds of “hello my name is Victoria, there is no problem with your credit card, but...” telemarketers) was able to spoof the caller ID system to show a local phone number. Why the 911 operator or other official up the line did not call back to verify the source of the call and information given is a problem. The SWAT team did not arrive on scene within seconds, rather it probably took a substantial amount of time to assemble the team and get them to the scene. This time could have been used to accumulate information on the situation.
To dispatch a lethal team on the basis of a single phone call is a serious lapse of control.