BP resumed a critical and repeatedly delayed test of its Gulf well Thursday after fixing a leak on the new cap designed to contain the gushing oil.

No oil is currently flowing into the Gulf for the first time since the Deepwater Horizon rig exploded April 20, killing 11 workers. BP could not guarantee that no oil would be released throughout the duration of the test, which will continue for at least 6 hours and could last up to 48 hours.

"It felt very good not to see any oil go into the Gulf of Mexico," BP senior vice president Kent Wells told reporters during a Thursday afternoon technical update. "Clearly, I’m trying to maintain a strict focus but we are very encouraged."

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