The total amount of oil spilled and whether the crude affected the snow-covered tundra nearby isn't yet clear, though authorities have expressed confidence the crude contamination is contained with a gravel area directly surrounding the well site.
"Crews are on the scene and are developing plans to bring the well under control, " said Brett Clanton, a BP spokesman, "and safety will remain our top priority as we move through this process".
Responders on Saturday night were able to enter the well house and connect hoses to valves.
A leak of natural gas from an Alaska North Slope oil well was plugged by pumping salt water down the well. The infamous Exxon Valdez, which in 1989 spilled tens of millions of gallons of oil into the Gulf of Alaska, was carrying oil extracted from Prudhoe Bay.
Media covering the accident recall that this is not the first spill for BP's Alaskan operations, which account for over half of the state's oil and gas output.
In 2010, a BP-operated drilling rig called Deepwater Horizon exploded, killing 11 people and spilling almost five million barrels of oil into the Gulf of Mexico, making it the largest oil spill in USA federal waters. Hilcorp Alaska has discovered several oil and natural-gas leaks in pipelines, but ice made had it impossible to fix the leaks. The gas, which comes up along with oil, is typically pumped back underground to squeeze more crude oil out of the reservoirs. In 2006, a corroded pipeline released almost 5,000 barrels of crude oil, the largest oil spill in the North Slope at the time.
The volume of the leak had not been determined and the cause of the release was unknown, according to a statement from the state's Department of Environmental Conservation. So far no injuries or wildlife impacts have been reported.