The damaged well is on state land several miles outside Deadhorse, a remote town.

“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.”

He said that it was unknown how much gas had leaked and that the company would investigate the causes of the accident after repairs were made.

Oil workers operating near the well were evacuated because of the possibility of an explosion.

There are large quantities of gas in the northern Alaskan fields around Prudhoe Bay in part because, without enough pipelines to bring it to market, oil companies have been pumping excess gas back into the ground for decades.

“The cause of the discharge is unknown at this time,” federal and state officials said in a statement late on Saturday. The statement said that an effort to secure the well on Friday night “was unsuccessful due to safety concerns and damage to a well pressure gauge.”

BP has struggled to repair its reputation since the disastrous Deepwater Horizon explosion and oil spill in the Gulf of Mexico in 2010 that killed 11 rig workers. The new leak in an established production well, however, has little in common with the blowout of the ill-fated well in the Gulf of Mexico. That well was drilled for exploration purposes, and the accident was caused by a series of errors by BP and its service companies.