Hail is precipitation in the form of a chunk of ice that can fall from a cumulonimbus cloud. Usually associated with multicell, supercell and cold front-induced squall line thunderstorms, most hail falls from the central region of a cloud in a severe storm.
If you are caught in a hailstorm:
Seek shelter immediately if you are outdoors. If you can’t find something to protect your entire body, at least find something to protect your head.
Stay out of culverts and lowland areas that might fill suddenly with water.
Stop driving. Pull safely onto the shoulder of the road away from any trees that could fall on your vehicle.
If at all possible, pull into a sturdy garage or under a shelter to minimize hail damage.
Do NOT leave your vehicle until it stops hailing. Your car will provide reasonable protection.
Sources: FEMA.gov, NOAA.gov
Remember: You are responsible for your safety and for the safety of those around you.