A week ago, the sanctuary at Notre Dame d’Haiti in Miami was immersed in intense prayer. The congregation gathered, hands open, in a long, rhythmic invocation in Creole for the preservation of Temporary Protected Status, which has allowed more than 330,000 Haitians to live and work lawfully in the United States for years.

Once Mass was over, the Rev. Reginald Jean-Mary said that all they were doing now was “praying and waiting.”

On Thursday, the long-awaited ruling by the Supreme Court landed like a bomb on the Haitian community in South Florida, the largest in the country. It quickly reverberated through Massachusetts; New York; Springfield, Ohio; and other places where Haitians have settled in large numbers.

Father Jean-Mary, after learning of the Supreme Court’s decision, seemed in shock. He declined to comment.

While focused on Haitians and several thousand Syrians with the protection, the court’s decision has implications for all 1.3 million T.P.S. holders in the United States, from more than a dozen countries. Many of them have been in the United States for decades.

Justice Samuel Alito, writing for the 6-to-3 majority, said that the courts were barred from reviewing the Department of Homeland Security’s process and determination to end a country’s T.P.S. designation.

The court rejected the Haitian plaintiffs’ claims that the administration’s decision was unconstitutionally motivated by racial bias.

Haitians who have been covered by T.P.S. were in disbelief. “I did not expect this at all,” said Sadrac Delva, a Haitian-born real estate agent in Springfield, Ohio, who was in the middle of closing on a house for a Haitian family when the ruling was issued.

Viles Dorsainvil, executive director of a Haitian community center in Springfield, where thousands of Haitians have settled in recent years, said: “Families are here. Folks are going to work. The Supreme Court just put all that at a stop and put all those people in limbo.”

It was not clear how quickly Haitians and Syrians would become vulnerable to removal from the United States, but the ruling makes them deportable. Their work permits will immediately expire, and they will lose their jobs and driver’s licenses.

Thamara Labrousse, executive director at Sant La Haitian Neighborhood Center in Miami, has been inundated with calls asking, “Will I lose my job? When does it go into effect? How much time do we have?” she said.

“There is a lot of anxiety because conditions in Haiti have gotten worse than when they granted the T.P.S. to begin with,” she said.

Some T.P.S. holders have pending asylum applications, but it remains unclear whether the administration will spare them from enforcement if they crossed the border unlawfully.

If a country in crisis receives a T.P.S. designation, its citizens already inside the United States are protected from deportation. They are allowed to stay and work, regardless of whether they originally entered the United States legally or not. The homeland security secretary typically decides whether to renew the status, which lasts 12 or 18 months, after reassessing conditions.

Geoff Pipoly, the lead litigator for the Haitians, said his heart was broken: “We did everything the law allowed us to try to do.”

“Many, many people are going to needlessly die,” he said, because Haitians would be forced to return to a country engulfed in violence.

He said that it now fell on Congress to protect T.P.S. holders. Democratic senators, led by Edward J. Markey, introduced a bill earlier this month to preserve legal status and work authorization for Haitians in the United States.

The Senate legislation is a companion to a bipartisan House bill.