Presumably the neighbours are away, if so is there not a contact for the alarm company ( on the external box) or, any contact for the neighbours so they could get a keyholder to turn it off. That would probably be the fastest solution. Thats usually what we do if such happens. CHeck with other neighbours and someone usually can get a contact for the house involved.
http://www.environ.ie/en/Environment/NoisePollution/PublicationsDocuments/FileDownLoad,1319,en.pdf
Also has information on where to complain on noise pollution. HOwever presumably neighbour are not deliberately letting alarm ringing just to annoy everyone so not sure what action if any might be taken.