The information in this report is preliminary and will be either supplemented or corrected during the course of the investigation.
On February 11, 2018, about 1:15 p.m. Pacific standard time, an Air Products and Chemicals, Inc. (Air Products) module of 25 horizontally mounted high-pressure gas cylinders loaded with 240 kilograms (kg) of compressed hydrogen, UN1049, caught fire while being transported by a 2014 Mack truck tractor in combination with a 2015 Cheetah intermodal chassis. The incident occurred on Golden Springs Drive, near South Brea Canyon Road, in Diamond Bar, California. About 120 kg of the hydrogen released from 12 of the cylinders that were exposed to the fire. The fire was extinguished, and the trailer was secured around 3:00 a.m. on February 12. No injuries were reported; however, about 500 persons within a 10-block business district were evacuated. Weather at the time of the incident was 69℉, maximum wind gusts were about 14 mph, there was no precipitation, and visibility was 10 miles.