American and Japanese visitors in particular canceled reservations, even though the site, perched on an isolated rock off the northwest coast of Normandy, is far from Paris. Gilles Gohier, the chief executive, said he had to tell nearly a third of his 230 employees to go home for four months, and temporarily shut half of his five hotels and four restaurants. Since then, he has eliminated 17 positions and is hiring new employees only on temporary contracts.

Business had just started to revive when the Bastille Day massacre in Nice happened. Cancellations jumped by 20 percent and were expected to rise further after this week’s killing of a priest near Rouen, located in lower Normandy, an attack carried out by militants claiming allegiance to the Islamic State.

“What happened in Rouen shows that it could happen here, or anywhere,” Mr. Gohier said. “This makes it impossible to plan for business in the future,” he added.

All of that has hit the European economy in one of its most vital sectors, tourism, just as a tenuous recovery was starting to take hold.

This year, growth in the 19 countries that use the euro returned to levels not seen since the 2008 financial crisis. On Friday, the European Union reported that the momentum slowed in the second quarter, as the economy advanced just 0.3 percent from April to June, down from 0.6 percent in the previous quarter. France slid back into stagnation with zero growth in the three months to June from the previous quarter.