What a mess, looks like all steel cars too. Was there any indication of what caused it? From the few pics you posted it looks like it may have started under the lift, as bent as those rails are that was a lot of heat. Since the metal on the other cars looks pretty good( not distorted like the lift), I was wondering the cause.
My first bike job in 1969 was at a BSA/Triumph/Yamaha dealer that had been an Indian dealer in the early days. It had a wooden floor that was pretty saturated from
oil over the years, it went up and there was little that could be done.
Oil saturated wooden floors are pretty hard to get put out.