A fire occurs naturally when the elements are present and combined in the right mixture, meaning that fire is actually an event rather than a thing. A fire can be avoided or extinguished by removing one of the elements of the fire triangle. For example, covering a fire with a fire blanket removes the oxygen portion of the triangle and can extinguish a fire. During major fires to which firefighters are called, reducing the amount of oxygen is generally not an option because there is no effective way to achieve this over an extended period of time..