A gas pipeline was not marked before soil testers began drilling in front of an Oak Cliff apartment building that leveled in a gas explosion that killed three people, according to a preliminary report released Wednesday by the National Transportation Safety Board.
A video recorded by the driller and obtained by KERA also appears to show the gas line was not marked.
The NTSB's report does not offer a cause of the gas explosion, instead largely providing a timeline of events. The detail about the gas line being unmarked was only mentioned in the footnotes of the report.
"Although the locations of some of the assets had been marked by painting and flagging, the location of this gas line had not been identified and marked," the report states.
A video taken by the driller shows that a gas line adjacent to the apartment was marked in yellow — the uniform color code for gas lines — but the drilling site itself showed no yellow markings.
An investigation by KERA found excavators in Texas have damaged pipelines more than 4,800 times since the beginning of 2026, frequently causing highly explosive gas leaks.
That includes over 1,000 incidents in Dallas, Tarrant, Collin and Denton counties.
A final report by the NTSB could take over a year.
The report states that Barba Drilling, contracted by Engineering and Consulting Services, was operating a drill rig for soil sampling near the apartment building before a gas leak was reported at 12:49 p.m.
An attorney for the apartment owner previously told KERA the soil testing was being done for a prospective buyer who was looking to redevelop the property.
At 12:51 Dallas Fire-Rescue notified natural gas company Atmos of a "cut line." Atmos arrived around 1:20 p.m., shortly after the explosion, according to the report.
The report does not state exactly when the gas was ignited.
Atmos isolated the gas leak by hydraulically squeezing the main line in two places after the company arrived on scene. The final squeeze was finished by 2:41 p.m., cutting off all gas to the building.
The report states the gas pipes involved were made of polyethylene and installed in 1988.
The incident remains under investigation while NTSB determines the probable cause.
This is a developing story and will be updated.
Dylan Duke is KERA's Breaking News Reporter. Got a tip? Email Dylan Duke at dduke@kera.org.
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