Three suspects were arrested early Sunday in connection with an attack on a synagogue in Sweden's second-largest city.

In all, about a dozen masked men threw firebombs at a synagogue in Gothenburg, multiple reports said. The attack took place around 10 p.m. during a party for about two dozen local youths.

No injuries were reported. Party attendees reportedly retreated to the basement for safety.

Police believe the burning objects were Molotov cocktails.

According to a police inspector, firefighters managed to extinguish the flames before the synagogue could catch fire.

In response to the attack, officials have increased security around the synagogue and the adjacent Jewish center in Stockholm.

Witness Allan Stutzinsky told TT news agency he saw a dozen masked youths who threw objects into the garden surrounding the synagogue.

Demonstrations have taken place in Stockholm and Malmo in the past week over U.S. President Donald Trump’s decision to recognize Jerusalem as the capital of Israel.

The Associated Press contributed to this report.