If you are under a tornado WARNING, seek shelter immediately!

If you are in:

A structure (e.g. residence, small building, school, nursing home, hospital, factory, shopping center, high-rise building)

• Go to a pre-designated shelter area such as a safe room, basement, storm cellar, or the lowest building level.
• If there is no basement, go to the center of an interior room on the lowest level (closet, interior hallway) away from corners, windows, doors, and outside walls.
• Put as many walls as possible between you and the outside. Get under a sturdy table and use your arms to protect your head and neck. Do not open windows.

If you are in:

A vehicle, trailer, or mobile home

• Get out immediately and go to the lowest floor of a sturdy, nearby building or a storm shelter. Mobile homes, even if tied down, offer little protection from tornadoes.

If you are:

Outside with no shelter

• Lie flat in a nearby ditch or depression and cover your head with your hands. Be aware of the potential for flooding.
• Do not get under an overpass or bridge. You are safer in a low, flat location.
• Never try to outrun a tornado in urban or congested areas in a car or truck. Instead, leave the vehicle immediately for safe shelter.
• Watch out for flying debris. Flying debris from tornadoes causes most fatalities and injuries.

Source: fema.gov