Boats and water? Yes. Flowers and water? Of course. Cars and water? Not so much. When pipelines burst in an underground car park, the released water combined with the insulation material of the ground, causing swelling. With nowhere to go but up, the parked cars’ roofs collided with the low ceilings of the parking garage. Further complicating things is the gas inside of the now trapped cars; the potential for an explosion is high. Much higher than the roof of the garage, that’s for sure.

Cars crushed at Crayford flats after water pipe bursts – BBC News