Immediately turn off the heat source and cover the flames with a metal lid or baking sheet to smother the fire. Never use water on a grease fire.
When oil or grease catches fire, it's crucial to act quickly and correctly. The first step is to immediately turn off the stove or heat source. This prevents more heat from fueling the flames. Next, smother the fire by depriving it of oxygen. The best way to do this is to carefully slide a metal lid or baking sheet over the pan, completely covering it. Leave the lid in place until the pan has cooled completely. This can take a significant amount of time, so be patient. Never, ever use water on a grease fire. Water will cause the oil to splatter, spreading the fire and potentially causing serious burns. If the fire is too large to handle safely, evacuate the area and call emergency services immediately. A fire extinguisher rated for Class B fires (flammable liquids) can also be used, but only if you are confident in its proper use and the fire is still manageable. Aim the extinguisher at the base of the flames, using a sweeping motion.
Keep a box of baking soda near your stove. If you don't have a lid handy, baking soda can be used to smother a small grease fire. Pour it generously over the flames. However, avoid using flour or baking powder, as they can be explosive.