Investigators have completed their investigation into the cause of the massive explosion and fire in northwest Portland in October.
The explosion occurred the morning of Oct. 19 at Northwest 23rd Avenue and Glisan Street.
The building was evacuated, but eight people, including three firefighters and two police officers, were injured in the blast.
On Monday, Portland Fire & Rescue arson investigators released their findings.
Investigators said an excavator struck a steel gas line, pulling the pipe out of its fitting that was farther underground. That started the release of natural gas.
The natural gas traveled underground near the pipe and entered the basement of a building at 500 N.W. 23rd Avenue.
The gas then ignited, causing the explosion. Investigators said the specific ignition source is unknown due to the number of possible electrical and other ignition sources in the basement.
Portland Bagelworks and Dosha Salon Spa were destroyed in the explosion.
Loy Clark Pipeline Co. released a statement following the explosion stating its electrical division crew was working on a construction site for a new building at Northwest 23rd and Glisan Street. The new building is a Bremik Construction project.
Bremik reported that the subcontractor immediately shut down operations and followed safety protocols when the pipeline was hit.
Portland Fire & Rescue was assisted by the Bureau of Alcohol, Tobacco, Firearms and Explosives and the Portland Police Bureau in the investigation.
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