Fires

You need to build more fire stations. Or, if you have a lot, they need to be near groups of buildings. In the move mode (or when you first build them) you see the building they service. It is highlighted in green. One quick fix is if you don't have enough money to build another one, move one you have to the building burning. However, then the other buildings may catch fire. Stop expanding your city or leveling up a building until you have enough fire houses to cover every area is the best way to let your city's resources catch up to the growth of its population.