Police have detained a suspect and are hunting for another after three people were shot dead and a fourth seriously wounded in an armed attack at the Jewish Museum in Brussels.

The bloodshed, which came on the eve of national and European Parliament elections, led authorities to immediately strengthen anti-terror measures.

Belgian foreign minister Didier Reynders, who was in the area at the time, said the scene “was terrible and left me shocked” as he saw the bodies of two of the victims lying at the entrance of the museum, in the capital’s upmarket Sablon neighbourhood.

Mr Reynders said “you cannot help to think that when we see a Jewish museum, you think of an anti-Semitic act. But the investigation will have to show the causes”.

Interior minister Joelle Milquet said the shooter apparently parked a car outside before entering the Jewish Museum. The gunman “apparently fired rather quickly, went outside and left”.

The three dead were two women and a man, all were struck by bullets in the face or throat, said Ine Van Wymersch, a spokeswoman for the prosecutor’s office.

She said one suspect was detained after he drove away from the museum around the time of the attack. A second person being sought for questioning fled on foot. Ms Van Wymersch said security camera footage was being studied to try to identify the person.

Prime minister Elio Di Rupo expressed support for the Jewish community and said “everything has been mobilised that can be mobilised” to bring the killer or killers to justice.

“All Belgians are united,” he said.

Israeli prime minister Benjamin Netanyahu condemned the attack, saying: “This act of murder is the result of constant incitement against Jews and their state.”

Ms Milquet said anti-terror measures had immediately been heightened as a precaution. “We decided to apply to a maximum level of protection to Jewish sites,” she said.

European Jewish Congress president Moshe Kantor said even though it had yet to be established whether the attack was anti-Semitic, “we are acutely aware of the permanent threat to Jewish targets in Belgium and across the whole of Europe”.

“European governments must send out a clear message of zero tolerance toward any manifestation of anti-Semitism,” he said.

Sablon was hosting a three-day jazz festival at the time of the attack, shortly before 4pm, and the area is usually clogged with tourists and shoppers at weekends. It has cobblestone streets with numerous antique shops and trendy cafes and museums, including theJewish Museum.

Viviane Teitelbaum, a member of the Brussels legislature, said anti-Semitic attacks had reached a peak in the early 1980s,then dropped off, but she noted a recent rise in anti-Jewish sentiment.

“It has been a very difficult place to live” for Jews, she said, adding that many young people were leaving the country. She said some 40,000 Jews lived in Belgium, half of whom are in Brussels.

Simone Susskind, another Brussels politician, said the museum had been at its current site for around a decade, after moving from an old synagogue in southern Brussels.

She said her late husband David was a driving force behind the museum’s creation, believing that as home of the European Union and self-proclaimed “capital of Europe”, Brussels needed a museum to recount the history of Belgium’s Jewish community.

In neighbouring France, President Francois Hollande condemned the “horrifying killings with the greatest force”.

Two Israelis were killed in the shooting, it emerged. Israel’s Foreign Ministry said they were a couple in their 50s from the Tel Aviv area.

Spokesman Paul Hirschson said the attack appeared to have been directed at Israelis or Jews.

He said: “An Israeli couple visiting the Jewish Museum leaves too much to the imagination.”