In one sentence, describe what the following article is about:

If you’re in an open area, drop flat to the ground to evade gunfire as soon as you hear shots. Try to determine where the shots came from, and move out of the line of fire to the nearest available cover.  Look for bushes, a brick wall, a ditch, or any other feature that puts you out of sight. If there's no cover within a two to three second sprint from your location, drop to the ground and crawl to cover. and contact emergency services. Once you’ve found cover or a relatively secure place, hide there, stay down, and don’t move. Don’t raise your head or peek out to see what’s happening. If you have a cell phone, call emergency services when you believe you can safely do so. If you’re hiding inside a car, stay down, as windows obviously offer no protection. If you're using a car as cover from shooting, do your best to get away from the area where the gas/petrol tank is situated, which is usually just ahead of the rear axle. Try to hide behind the engine block by one of the front wheels.
Drop, then quickly move to better cover. Hide Hide near the engine block when using a car as a barricade.