shopping at night

It was so hot today that I had to let Lynettea go down the street to do her supermarket  hunting at night. At least it was not quite night, but late on a summer day. She was surprised that few people were there. The checkout lady told her there had been a nasty accident in the afternoon, with water pouring from the glass atrium roof onto the pretty  clothes and shoes in one store and all over the Wendys' icecreams in another. Then the water  ran down the escalators and stopped them  working.
where did the  water come from?
I was glad to see her home safe.