WW2 FIRE SIREN: 3 minutes WARNING

A further important siren signal for civil protection in Austria, called "warning":
A 3 minutes continues siren sound without breaks:
What to do in such case???
-- Turn on radio/TV
-- Wait for intructions
In my video you can see/hear an old&loud ww2 fire-siren. This electro-mechanical siren was constructed by Siemens (Fm Si40) in the 30ies and it has 3 ports. (deep tone frequency at 145 Hz)