Authorities say an oil spill near Prudhoe Bay contaminated about 8,400 square feet of snow-covered tundra.

Alaska Department of Environmental Conservation spokeswoman Weld Royal said oil cleanup crews rushed to the scene about 1 1/2 miles from a production center on the North Slope around 3 a.m. Sunday.

She told The Associated Press that it still isn't clear how much spilled or what caused it, but the petroleum did not reach the bay.

The spill occurred around an 18-inch pipeline that carried a mixture of crude oil, produced water, and natural gas, but the line was not in operation at the time.