NEW ORLEANS (AP) - After five months, the oil well that had spewed millions of gallons into the Gulf of Mexico is on the verge of being plugged once and for all.

A relief well drilled nearly 2.5 miles beneath the floor of the Gulf of Mexico intersected BP's blown-out well, a prelude to permanently killing it, the U.S government said late Thursday.

Retired Coast Guard Adm. Thad Allen, the government's point man on the oil spill, said in a statement that data shows the two wells are joined. The next step will be to pump mud and cement down through the relief well to seal the ruptured well from the bottom.

The final seal should happen by Sunday, five agonizing months after an explosion killed 11 workers, sank a drilling rig and led to the worst offshore oil spill in U.S. history.