After 85 days of planning, cleanup and failed repair attempts, BP said Thursday it has finally stopped the flow of oil from its ruptured Gulf of Mexico oil well.

BP Senior Vice President Kent Wells announced that no oil was flowing into the Gulf shortly after BP launched an “experiment” designed to measure pressure within the ruptured oil well. Earlier this week BP successfully closed the last of three openings in the 75-ton cap which was lowered onto the well.

Wells said the test will show how well the capped-off well is holding. Higher pressure readings mean the well is containing the oil, while lower pressure means some is leaking out.

“For the people living on the Gulf, I’m certainly not going to guess their emotions,” Wells said. “I hope they’re encouraged there’s no oil going into the Gulf of Mexico. But we have to be careful.”

The live underwater video feed that has permeated news broadcasts for the past three months confirmed the gusher had been stopped.

The cap is likely not the permanent fix to the leak, however. The company is drilling two relief wells to pump mud and cement into the leaking well in hopes of plugging it permanently by mid-August.

“Depending on what the test shows us, we may need to open this well back up,” Wells said.

BP Chief Operating Officer Doug Suttles said it is too soon to conclude definite results, reminding that “this is a test,” but BP and government officials have begun a 48-hour watch period to see whether a new leak develops. Officials will formally review data every six hours, according to Suttles.

President Barack Obama called it a positive sign, but said that he’d have more to say Friday.

“We’re still in the testing phase,” Obama said.

The biggest risk BP is facing is that pressure from the oil gushing out of the ground could fracture the well and make the leak even worse.

According to government estimates, between 94 million and 184 million gallons of oil have spilled into the Gulf since the April 20 explosion on the Deepwater Horizon oil rig that killed 11 workers.

Wells said that “it felt very good to see no oil going to the Gulf of Mexico” but said BP is still “trying to maintain a strict focus.”

“I don’t want to create a false sens of excitement,” he said. “We want to move forward and make the right decisions.”

According to CNN, the “well integrity” test could end after six hours or it could go on for 48 hours depending on the results. The longer it goes, the better the indications that the well is holding with a custom-made sealing cap.

BP said the oil cutoff will not go more than 48 hours because valves will open in order to resume siphoning oil to two ships on the surface, the Q4000 and Helix Producer, while officials decide what to do next.

BP’s stock, which has been dropping since the spill began, closed nearly 8 percent higher on the New York Stock Exchanged after the news.