VIENNA (AP) — Austrian police issued a terror threat warning Thursday for Vienna, saying there was an “abstract” danger for Syrian institutions in the city.

The alert came a day after police in Austria’s capital warned of ” a possible “Islamist-motivated attack” on churches and other houses of worship, citing undisclosed information received by the country’s intelligence service.

In an update, the police department said “a recent threat assessment” by the intelligence service indicated the warning was “particularly related to the anniversary of the civil war in Syria — it primarily concerns Syrian facilities.”

“The potential threat is still on an increased level,” the department tweeted Thursday. “The preventive security measures ordered remain in place. We are in contact with representatives of the corresponding facilities.”

Despite Wednesday’s initial warning, churches and houses of worship in Vienna remained open to visitors and worshipers. Police patrols were increased across the city, but no unusual incidents were reported.

Police said Thursday that “as soon as the respective assessments indicate an easing of the situation, we will be able to reduce our safeguarding measures.”

The Associated Press