it was caused by the squatters illegally storing fuel and a generator while also actively shooting the police, fire department, and medical rescuers. The police didn't cause them to shoot. It was their own terrorist doctrine that told them they could. It wasn't the police who stored fuel or a generator illegally in the building, that was the terrorists. It wasn't the police who used a standard tactic for entry into a building with an active standoff that caused the fire but the terrorists who decided they knew better than the fire department, health and safety department, etc... and stored fuel at the top of the building which happened to catch fire through the use of the standard entry tactic the police used.