[1] A report from NIST was also unable to determine the exact source, but agreed it likely originated in electrical equipment, and likely one of the computer workstations.

[5] Around 50 people were believed to be occupying the building at the time of the fire, with 37 individuals injured including 3 firefighters.

One firefighter with the Los Angeles Fire Department told reporters; "I was not sure we could hold it" due to the intensely hot blaze fueled by the synthetic fabrics and furnishings in the building.

According to the US Fire Administration report, unusually good application of fireproofing on support members was a significant mitigating factor.

[1] The fireproofing used to protect the steel was Monokote supplied by GCP Applied Technologies (formerly W. R. Grace).