The PUC (Oregon Public Utility Commission) determined the cause to be inadequate notification by the contractor, Loy Clark Pipeline.

The pipe did not break, but was pulled out of a valve some distance away, causing leaking gas to travel under the sidewalk and fill the basement of 500 NW 23rd Avenue.

A limited number of firefighters (three engines and one truck) showed up and Battalion Chief Scott Beyers made the call to evacuate the businesses and residences near the intersection where the leak occurred.

[7] About 420 students at Metropolitan Learning Center, many of whom were in the process of taking their PSAT tests, were evacuated and transported to the Portland Public Schools headquarters as a precaution.

[9][10] Loy Clark Pipeline was founded in 1957 and in 2016 was a part of Bismarck, North Dakota-based MDU Construction Services Group, Inc.[11][12] The Oregon Public Utility Commission concluded "Insufficient Notice to the Oregon Utility Notification Center by Loy Clark Pipeline Co." as the root cause.

[2] KATU reported that Loy Clark Pipeline in five years leading up to the accident had six OSHA violations.

[19] The Oregonian reported in December 2019 that two additional businesses, Portland Bagelworks and Dosha SalonSpa, had filed lawsuits.