This is the traditional siren used by Italian EMS or Fire Brigade vehicles to grab the attention of motorists and pedestrians. It is especially effective purely because the sound is so annoying that you just have to know where it's coming from.
Example Video:
Credit goes to Fiamme Siren Co. for the sound byte, used with permission
Italian EMS/Fire Brigade Siren 1.0
The easiest way to annoy thousands of people at once
