Changzhou Lighting Factory caught fire and four people lost contact. What was the cause of the fire?

Because of the hot weather in summer, there will be a lot of flammable materials, which will spontaneously ignite after being irradiated by the sun. It is also possible that electricity is used carelessly, and many electrical equipment is overloaded, which will cause a fire. If you don't pay attention to using fire in your life, it will also cause fire. Many people throw cigarette butts on the grass after smoking outdoors, which may also cause fires. Children playing with fireworks can also cause fires.