Idiot tenant flooded 3 flats

Maintenance

Hi there,
We own a flat in a georgian house which is part of a terrace. The top flat tenants blocked the gulley that moves the water along the terrace. They put a full hoover bag in it(just outside their window)which swelled up and dammed the gulley. All of this the night of the lightening storms and torrential downpour. The water poured through the house damaging three flats before we managed to get access to the top flat and remove the hoover bag.
Two questions: Would you expect the tenants or landlord of the top flat to be liable for repairs? And secondly would you expect the tenants of the damaged flats to be recompensed for the fact that they were unable to use their bedroom for a week or so and for 48 hours had no power in the flat?
All advice gratefully received