BP finally stopped the flow of oil into the Gulf of Mexico on Thursday – 85 days and 184 million gallons after the Deepwater Horizon oil spill began on April 20, the Associate Press reported.

Now begins a 48 hour wait to see if the capped-off well holds or blows a leak, as engineers monitor pressure gauges and watch for signs of leaks elsewhere in the well.

The biggest risk is pressure from the oil gushing out of the ground, which could fracture the well worsen the leak.

“For the people living on the Gulf, I’m certainly not going to guess their emotions,” BP vice president Kent Wells said. “I hope they’re encouraged there’s no oil going into the Gulf of Mexico. But we have to be careful. Depending on what the test shows us, we may need to open this well back up.”

President Barack Obama called the capped-off well a positive sign, but cautioned, “We’re still in the testing phase.”

Assuming the cap succeeds, it’s still not a permanent fix. BP is drilling two relief wells so it can pump mud and cement into the leaking to hopefully plug the leak permanently by mid-August. After that, the Gulf Coast faces a monumental cleanup and restoration that could take years.

BP stock, which has fallen since the spill, closed nearly 8% higher on the New York Stock Exchange after the news.

Randall Luthi, president of the Washington-based National Ocean Industries Association, a national trade group representing the offshore oil industry, noted, “This is by far the best news we’ve heard in 86 days. You can bet that industry officials and their families are taking a big sigh here.”