(CNN) Police are guarding Jewish centers across the Swedish city of Gothenberg following an arson attack on a synagogue there, police said.

Three men, all in their twenties, have been detained for questioning in relation to the Saturday night incident, police said.

Spokeswoman Ulla Brehm said that police received reports shortly after 10 p.m. local time that burning objects had been thrown into the yard of the synagogue, causing a fire. Brehm said approximately 10 people dressed in black were seen running away after throwing the objects.

No one was injured in the attack and the projectiles thrown did not make it inside the synagogue. Police are not describing the objects as Molotov cocktails.

Authorities used surveillance camera footage to identify the three men who are being questioned. The police are not reporting their nationalities.

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