KENNER, La. – The U.S. government’s point man on the Gulf of Mexico oil spill said Wednesday that BP’s blown-out well is expected to be permanently sealed by Sunday, nearly five months after a rig explosion set off the disaster.

National Incident Commander Thad Allen told reporters gathered at a Kenner seafood distributor that a relief well is expected to intersect with the blown-out well within 24 hours. He said mud and cement will then be pumped in, which is expected to seal the blown-out well within four days.

“We are within a 96-hour window of killing the well,” Allen said.

The April 20 explosion killed 11 workers and led to 206 million gallons of oil spewing from the undersea well.

No fresh oil has spewed into the Gulf since a temporary cap was successfully fitted to the top of the well in mid-July. Mud and cement were later pushed down through the top of the well, allowing for the cap to be removed. The relief well is being drilled so the well that blew out can also be sealed from the bottom.

Appearing with Allen, National Oceanic and Atmospheric Administration chief Jane Lubchenco said monitoring continues of oil that remains in the Gulf. Lubchenco stood by earlier government estimates that 50 percent of the oil that spilled is gone from the water system.

Scientists said earlier this week that they had found thick patches of oil coating the sea floor.