In the case of most major emergencies, the simple advice to follow is go inside, stay inside, and tune into local radio, or in the case of a burning building, get out and stay out.
With most incidents the safest place to be is indoors, and with correct preparation you should be able to stay there safely for some time.
To help you know what to do, listen to local radio for advice and information. Radio is easily accessible and as long as you have a battery powered or wind-up radio, you can still listen even if there is a power cut.
Radio stations covering the Caerphilly county borough area: