Investigators believe a deadly underground fire at Thanksgiving Tower was started by sparks landing on a plastic liner or some sort of gas.
Oscar Esparza-Romo, Luis Carillo and Nicasio Carrillo were working in the basement when the fire began in Dec. 2014.
An administrative report found that they were using a torch to remove corroded metal from an empty water cooling tank. This is work they apparently did not have a permit to do.
The fire started within the tank, possibly from sparks igniting the plastic floor liner that coats the container on the bottom and sides.
The men got trapped 35-feet underground in the Thanksgiving Tower garage and died of smoke inhalation.
The fire also caused roughly $20,000 worth of damage to the building.