A federal official said crews in Alaska are trying to shut down an oil well that is leaking explosive natural gas on the frozen North Slope.

The Environmental Protection Agency said a crack in a BP wellhead near Deadhorse sent up mist of crude oil on Friday before it froze over and an initial leak stopped.

BP spokesman Brett Clanton said that “based on an overflight with infrared cameras, the release appears to be contained to the gravel pad surrounding the wellhead and has not reached the tundra.”

Clanton said BP is focused on safely securing the well.

However, agency spokeswoman Suzanne Skadowski said a second crack was discovered that’s releasing flammable, explosive gas.

It’s unclear how much has vented, but nearby workers have been evacuated and native Alaskan villages dozens of miles away have been notified.

No injuries have been reported.

There were no reports of damage to wildlife.

The agency said the initial oil release may have affected an area of about one-and-a-half acres.

Skadowski said the EPA, state and BP hoped to shut down the well on Saturday.