Thousands of people are killed or injured around the world every year from lightning strikes. When working outdoors be sure to have a plan whenever you hear the roll of thunder. The sound of thunder is your best indication that lightning is close enough to strike you. When outside, your first reaction should be to stop what you are doing and get everyone into a safe shelter. Even though threating clouds may appear to be far away, lighting has been known to travel 10 miles before it strikes. Safe shelters include substantial buildings (ones that are enclosed and grounded) or fully enclosed metal vehicles. If a safe shelter is not available avoid high grounds, tall metal objects (e.g., drill rigs, power polls, or cell towers), bodies of water and tall isolated trees.