Well, I hope no one was seriously hurt. Its hard to tell from the pic, but seeing the frame damage in the grip area, I wonder if a case head let go. The pistol may have fired before being in complete battery. I once owned (now in the bottom of a lake) a Taurus 9mm pistol that would unlock before pressure had dropped, causing a case head blow out. Fortunately the gun held together, with most of the damage confined to the grip area and the magazine.
Larry