Faulty hydraulic tubing is believed to be the cause of a large fire that erupted early Saturday at an eight-well pad operated by Statoil ASA, according to state regulators.

No serious injuries were reported. The company said its wells were not damaged, but the fire destroyed surface equipment and jolted nearby residents who reported hearing explosions.

Ohio Department of Natural Resources (ODNR) spokeswoman Bethany McCorkle said 16 pump trucks and four blender trucks were a “total loss.” She added that a fish kill in a nearby creek could be related to the incident as well.

Statoil spokesman Bjorn Otto Sverdrup said crews were able to shut-in the wells before they were damaged. In addition to personnel evacuating the site, a voluntary evacuation order was issued for nearby residents and five families stayed the night at an area high school.

Otto Sverdrup said crews, trucks and other equipment were at the site making preparations for the hydraulic fracturing of seven wells at the Eisenbarth well pad in Ohio Township, near the West Virginia border. The eighth well at the pad had been producing for some time, he said, but it was plugged for those operations.

Officials from ODNR, the Ohio Environmental Protection Agency and the U.S. Environmental Protection Agency were called to the scene, with some still working on remediation efforts Monday, McCorkle said. Otto Sverdrup said operations will resume at the site after a full investigation is completed by the authorities and the company.

He added that the fire was the largest U.S. onshore emergency to date at any horizontal shale drilling site operated by the Norwegian multinational.

The incident marks the third major well site emergency in the Appalachian Basin in the last five months. In February, two wells operated by Chevron Appalachia LLC caught fire after an explosion that killed one worker in Pennsylvania (see Shale Daily, Feb. 11). In April, a subcontractor was killed by heavy equipment at Rice Energy Inc.’s Bigfoot 9H well in Belmont County, OH (see Shale Daily, April 7).