NEW ORLEANS -- The Coast Guard says BP has been forced to remove a cap that was containing some of the oil gushing into the Gulf of Mexico.

Coast Guard Adm. Thad Allen says an underwater robot bumped into the venting system. That sent gas rising through vent that carries warm water down to prevent ice-like crystals from forming in the cap.

Allen says the cap has been removed and crews are checking to see if crystals have formed before putting it back on. In the meantime, a different system is still burning oil on the surface.

Before the problem with the containment cap, it had collected about 700,000 gallons of oil in the previous 24 hours. Another 438,000 gallons was burned.

The current worst-case estimate of what's spewing into the Gulf is about 2.5 million gallons a day.