Union Pacific said as many as 10 train cars derailed at about 6:15 a.m. The south side of the bridge then collapsed and caught fire. A spokesman said its crew was not hurt but one person at the park was treated for smoke inhalation. (Click video player below for first reports.)
Union Pacific spokesman Tim McMahan said two of the three tanker cars on the ground under the bridge contained cyclohexanone. The third contained a rubber material. "None are reported leaking, and no tank cars were involved in the fire," he said. According to the National Center for Biotechnology Information, cyclohexanone is a colorless oily liquid that is both flammable and an irritant. It's mostly used for the production of nylon.
The cars that burned for hours were carrying lumber, some of which fell into the lake.
https://www.azfamily.com/news/train-derailment-massive-fire-on-bridge-over-tempe-town-lake/article_ce292ef0-d19e-11ea-a57f-7bc720db639f.html 