Same thing happened in at my work place. Some kid was drunk, being chased by cops, and crashed his car into the building next to my work. Car crashed, flipped, and caught on fire, he burned alive. They claim he had gotten away from them and they saw nothing. It was reported by people driving past as in your case, but there were holes in their story and evidence of the contrary. My boss had disconnected the front cameras a bit prior and hadn’t gotten around to reconnecting them, unfortunately, so we’ll never know :(