Engineers working to stem the flow of oil from the well 5,000 feet below the surface decided to remove the cap after a drone submarine came into contact with the device. The system was back in place later in the day.
The containment system has shown success in capturing much of the oil leaking from the well, which was below the Deepwater Horizon rig. An explosion April 20 on the rig killed 11 workers, caused the rig to sink and has led to millions on gallons of oil escaping the wellhead.
BP, the company that operated the rig at the time of the explosion, said it was continuing efforts to drill a pair of relief wells to cut off the flow of oil but those wells aren't expected to be completed for more than a month.
Oil is still escaping attempts to control the spill and millions of barrels of oil have fouled large expanses of the Gulf of Mexico. Officials have banned fishing on about a third of the federal waters. A flotilla of surface ships continues to corral the oil with booms and skimming. Workers on land are cleaning areas where the oil has reached shore, polluting sensitive wetlands and killing wildlife.