The Pasadena Fire Department confirmed the accident happened at about 12:30 p.m. at a Chevron property on Red Bluff near Highway 225.
Authorities said of the three contractors hurt in the incident, one was airlifted by Life Flight with serious injuries, and the other two were taken by ambulance with non-life-threatening injuries.
It's unclear what led to the collapse, but an investigation is underway.
In a statement sent to ABC13, a company spokesperson confirmed the contractors were hurt during demolition work, saying, their "thoughts are with the affected individuals" and that "safety is Chevron's top priority."
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