If you are in a car which has come in contact with a downed power line, stay in your vehicle.
If you are driving and come upon a downed power line, stay in your vehicle, warn others to stay away and contact emergency personnel or the electric utility. Never drive over a downed line. A downed line causes other things around it to become potentially hazardous.
Remain calm, stay in the vehicle and call for help. Ask someone to call the electric utility, and a lineman will be sent to disconnect the power. If the power line is energized and you step outside, your body becomes the path and electrocution is the tragic result. Wait until the electric utility arrives to make sure power to the line is cut off.
Even if a power line has landed on the ground, there is still the potential for the area near your car to be energized. Stay inside the vehicle unless there is fire or imminent risk of fire. Be sure that at no time you or anyone touches the equipment and the ground at the same time. You should never simply step out of the vehicle. If you must leave your car jump free keeping both feet together and either shuffle or hop to safety. A live wire touching the ground causes electricity to fan out in a pool and the action of running or striding allows one foot to move from one voltage zone to another. Your body then becomes the path for the electricity and electrocution is the tragic result.