Faulty wiring accidentally started the LaSalle Bank building fire, causing a blaze that consumed the 29th floor of the historic skyscraper and imperiled the lives of hundreds of people working late that night, investigators believe.
Fire investigators will continue testing evidence from the Dec. 6 fire at 135 S. LaSalle St. for several months, but Chicago Fire Department officials were confident enough Tuesday to say some unknown but accidental defect caused the electrical wiring to ignite plumbing insulation and ceiling tiles.
The fire blazed for more than four hours, and more than a dozen floors above the 29th were filled with smoke, but no one died. And though Fire Commissioner Cortez Trotter lauded rescuers and command staff--especially for implementing lessons learned from the tragic 69 W. Washington St. fire in October 2003--he also announced several new procedures for fighting high-rise fires.
A series of department self-critiques prompted the changes, Trotter said. The final critique will be carried out Wednesday when officials meet again with bank employees.
The new procedures include using helicopters with infrared imaging cameras to see into the burning upper floors of skyscrapers and placing emergency medical service workers closer to the burning floors so they can assess and treat the injured faster.
"It is my belief that the fire at 135 S. LaSalle St. was handled well, as a result of actions by both firefighters and building personnel," Trotter said. "But, as I've stated before, we can always find ways to do better."
As fire officials continue to learn from the blaze, they also put together a detailed account of what they think happened, said Lt. Anthony Martin, who led the probe.
The conclusion of an accidental electrical fire "is based on a thorough fire-scene examination, credible witness statements, testing by the state crime lab and the opinion of an electrical engineer" flown in from the U.S. Bureau of Alcohol, Tobacco, Firearms and Explosives' fire research laboratory in Washington, Martin said.
"While there may be further testing of electrical components from the area of origin, the results of this testing could take several months," he said.
ATF fire investigator John Gamboa stressed that pending tests "may never pinpoint exactly where or why [the electrical wiring] failed."
About 500 people were still in the building when the 29th floor began to fill with smoke shortly before 6:25 p.m. on that Monday.
Once the fire ignited above the ceiling, the tiles became unhinged and flapped open, dropping burning debris onto the floor of the bank's corporate trust sales office, Martin said.
Shortly after escaping, LaSalle employee Susan Keizer said she had been working late, walked around a corner and saw flames leaping from a table with gift baskets on it.
On Tuesday, fire officials said they believed the table caught fire after burning debris dropped from the ceiling.
The ATF's electrical engineer decided the problem was in the wiring in the ceiling above the table, Martin said.
In the LaSalle Bank fire, the Fire Department used some of the lessons learned in the 69 W. Washington fire, which killed six Cook County employees who became trapped in smoky stairwells.
Although several people suffered smoke inhalation in the LaSalle Bank fire, everyone survived, and Trotter credited a new system of searching the smoky floors with special rescue teams.
Another lesson the department learned after the LaSalle Bank fire is to set up a better system of identifying injured fire and rescue personnel, Trotter said.
The Fire Department plans to issue dog tags to firefighters to identify and account for them more easily during crises.