Ms. Brehm, a spokeswoman for the police in Region West, said Gothenburg officers received a call about the episode after 10 p.m. Saturday. She the suspects were dressed in black and wearing hoodies.
“They ran away, and shortly thereafter we got hold of three of them,” she said.
The police arrested three men in their 20s on suspicion of arson, Ms. Brehm said, adding that they were looking for other suspects. The police did not release further details about the suspects.
Swedish leaders condemned the attack on the synagogue. Prime Minister Stefan Lofven said in a statement on Sunday: “There is no place for anti-Semitism in our Swedish society. The perpetrators will answer for their crimes.”
Foreign Minister Margot Wallstrom tweeted: “The attack against the synagogue in Gothenburg and threat of violence against Jews in Malmo is deplorable and totally unacceptable. Anti-Semitism, threats and violence have no place in our society.”
The Police Authority’s commissioner, Dan Eliasson, told the Aftonbladet newspaper that the threat level against Jewish interests in Sweden had increased since President Trump’s announcement that the United States would recognize Jerusalem as the capital of Israel.
The attack in Gothenburg came a day after demonstrators took to the streets ofMalmo, Sweden’s third-largest city, shouting slogans about killing or shooting Jews.
Calle Persson, a spokesman for the police in Malmo, said about 200 people gathered in the Mollevangstorget square in central Malmo on Friday afternoon to demonstrate against Israel.
“They had Palestinian flags,” he said. “They sang and among other things they yelled that they were going to shoot Jews.”
He said officers were scouring video footage of the demonstration and investigating reports of hate speech. A similar demonstration was held on Thursday, he said.
But at a demonstration outside the United States Embassy in Stockholm on Saturday, a speaker with a Palestinian scarf wrapped around his neck told the crowd: “There is no room for anti-Semitism here. Anyone who expresses those sentiments should leave.”
Fredrik Sieradzki, a spokesman for the Jewish Community Center in Malmo, said the threat against Jews had been heightened after the demonstrations. “Then this happened in Gothenburg,” he said.
He said Jewish leaders had met recently with representatives with Muslim and Palestinian organizations in Malmo. “They wanted to show that they do not accept violence, threats of violence or discrimination against Jews in Malmo,” Mr. Sieradzki said.
Malmo has seen the highest incidence of anti-Semitic incidents in recent years. “That’s why we’re trying to do something about it together with the City of Malmo,” Mr. Sieradzki said.
A local police chief in Gothenburg told the TT wire agency that Jews in Sweden might fall victim to attacks from leftist extremists angry at Israel, from anti-Semitic right-wing groups or from Muslim extremist groups.
The Jewish population in Sweden numbers about 18,000, according to the Jewish Museum in Stockholm.
In September, a neo-Nazi group wanted to march by the Gothenburg synagogue while Jews worldwide were celebrating Yom Kippur. A local court denied their request.