A small blast outside a pro-Israel Christian center in a central city in the Netherlands is under investigation.

The explosion on Friday night caused limited damage at the Israel Centre, which is run by Christians for Israel, a non-profit in the city of Nijkerk, police said. No one was injured.

Police appealed for witnesses and said nobody has been arrested.

“Investigations revealed that a person dressed in black placed the explosive device,” the police added in a statement.

In a statement on its website, the group expressed shock and said the blast fits a pattern of attacks on Jewish sites that are intended to sow fear.

“The damage was limited, but the impact is significant,” the group said in a social media post, according to AFP. “The fact that this took place on the eve of Easter, the most important celebration for Christians, makes it all the more poignant.”

Police cautioned it was too early to determine a motive for the incident. An investigation was ongoing and no arrests have been made so far, they added.

The incident comes after a string of similar nighttime attacks in Belgium, Britain and the Netherlands that have heightened concerns over antisemitism in the wake of the war in the Middle East.

Ambulances run by Jewish volunteers were set on fire in London, a car was torched in Antwerp, synagogues were hit with explosives in Liege and Rotterdam, and a Jewish school was targeted in Amsterdam, since the U.S.-Israeli war against Iran began in late February.

The attacks have been claimed by a little-known Islamist group with possible links to Iran.