BISMARCK, N.D. (AP) — Natural gas flares at oil wells sparked two North Dakota wildfires earlier this fall, according to reports from the North Dakota Fire Marshal’s Office.

Investigators concluded that flares combined with high winds and extremely dry weather and started a wildfire near the town of Keene and another near New Town, the Bismarck Tribune reported Thursday. Officials with ConocoPhillips and Hess Corp., which operate the oil wells, say they are still reviewing the reports.

No one was killed or injured in the two fires that both began Oct. 5, but a combined 14 square miles (36.3 square kilometers) were burned, damaging land and livestock.

The fires were among several in northwestern North Dakota in October that burned up to 118,000 square miles (477.6 square km). Two people died and six were injured in other North Dakota wildfires. Agencies are still investigating what caused the other fires.

Flaring is the act of burning off excess natural gas that comes up along with oil. Oil and gas companies are required to flare natural gas from oil wells that cannot be captured or moved — venting natural gas is illegal and creates more pollution than flaring it.

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ConocoPhillips spokeswoman Lexey Long said the company is still reviewing the fire investigation report. The company is committed to providing information to the state fire marshal’s office and is working directly with landowners and tenants, Long said in a statement.

“Our focus remains on the safety of our workers, the community and on the protection of the environment,” Long said.

Hess spokeswoman Alison Ritter said the company “is in the process of reviewing the report” and declined further comment.

The fire marshal’s office does not issue penalties or have the power to prosecute. It is unclear if either company will face consequences.