Didn't something like this happen at Summerland?
The benefit of only one person on site/investigating is that he/she cant silence it again if it triggers again.
Summerland wasn't a hotel, but a leisure centre without sleeping accommodation.
A disused kiosk was set alight outside the building; several people used a hose-reel on the outside fire, not realising that the fire had penetrated the exterior wall. The alarm was not activated until the fire broke out of the hollow wall construction into the building with considerable violence - and promptly destroyed the fire alarm system wiring - so if the alarm did sound it was only for a few seconds.
The 'fire team' had never had proper training.
The management didn't think to remove the disused kiosk.
The external wall was changed from reinforced concrete to a coated steel sheet without reference back to the Fire Brigade....
and quite a few other failings in design and management of the building all added up to 50 deaths.