Video Footage from our battery powered NVR boxes

1- Video of exactly when transformer blew (with two flashes recorded)
(this camera is focused to record vehicle activity around our building)

 2- Video of 2 employees walking into building.  
First few seconds you can see the lights are powered ON.  Look at the side of our building to see.  There are employees working inside at the time.

Next, two employees arriving to work see flashes and hear the blow.  Instead of entering the side employee door, they walk to the front to investigate.  Notice the lights are now off on the side of the building because power was lost to entire building.