Oil gushed unchecked from the leaking well in the Gulf of Mexico after a robot submarine crashed into BP's containment system.
'We had an incident earlier today, they noticed that there was some kind of a gas rising,' said Admiral Thad Allen, the US official coordinating the response to the disaster.
'They indicated the problem was a remotely-operated vehicle had bumped into one of the vents,' Allen said, adding that the 'top hat' container was being checked and could be reinstalled later on Wednesday.
That would leave crude gushing into the ocean at a rate of between 30,000 to 60,000 barrels a day, according to the latest US government estimates. The containment system had been capturing roughly 25,000 barrels every 24 hours.
The containment system, which works by trapping leaking oil and then siphoning it up to a container ship, was shut down after gas was detected in a part of the unit that contains warm water, which is intended to prevent icy hydrates from forming and clogging the system.
Allen said the collision with the robotic submarine, which is operated from the surface by remote-control, appeared to have closed a vent, creating pressure that pushed material up into the water unit of the containment cap.
The cap was being examined and if no hydrates were found reinstallation would begin later on Wednesday, Allen said, warning that if the siphon pipe had to be refitted the operation, 'will take a considerable amount longer.'
In a day of bad news for the oil spill response, Allen said two people involved in the containment and clean-up efforts had been reported dead.
One was killed in what he described as 'an accident regarding a swimming pool,' but no details were provided about the death of the second individual, who had been working off the Mississippi shore, Allen said.
He offered his condolences, and said police were investigating the second death.
