Three people were killed on-site and another fatally wounded when a gunman attacked the Jewish Museum in the center of Brussels on Saturday, authorities said.
"Two women and one man are dead, a third person is in hospital," Interior Minister Joelle Milquet said at the scene, shortly after the attack. "We don't yet know if they were tourists or staff, they haven't been identified."
Asked whether she believed it was an anti-Semitic attack, she said it was too early to say as a police and judicial inquiry was under way but that given the target "there are strong grounds for presuming so."
Reports said the driver has been picked up within three hours of the shooting, which took place at around 4 pm (1400 GMT). There was no confirmation from police.
A bystander, Alain Sobotik, told AFP he saw the corpses of a young woman and a man just inside the doors of the museum.
A picture shows them lying in pools of blood.
Later Saturday, authorities announced that a suspect has been arrested. The injured victim was announced dead late Saturday, just before 11 pm Israel time.
"A person left the scene in their vehicle. We have identified and arrested them. But we do not know if they have a link to the events," a prosecution spokeswoman told a news conference, adding that the person was being "heard as a suspect."
The attack comes on the eve of elections in Belgium for a new federal government as well as for its regional parliaments and the European Parliament.
Crime or terror?
A Jewish community figure, Joel Rubinfeld, told AFP it clearly "is a terrorist act" after two men were seen driving up and double-parking outside the museum.
The gunman opened fire, allegedly shooting indiscriminately before getting away.
Rubinfeld, who heads the country's anti-Semitic League, said the act was the result of "a climate of hate."
Belgian Foreign Minister Didier Reynders was at the scene shortly after the attack, and told reporters that the two other victims had been shot inside the museum. "I hope we will identify those responsible very quickly," he said.
Reynders said he had been nearby when he saw people fleeing and heard shots and rushed to help. When he saw "bodies on the ground in pools of blood" he called the 112 emergency number and rounded up eye-witnesses to assist the police.
Police quickly cordoned off the area.
"I am shocked by the murders committed at the Jewish museum, I am thinking of the victims I saw there and their families," Reynders said on Twitter.
The Jewish Museum of Belgium, which was not answering calls, is located in the heart of the Sablon district which is home to the city's top antique dealers. It is a popular weekend haunt for shoppers and holidayers, hosting the city's best chocolate shops and many cafes.
The head of Belgium's Jewish Consistory told La Libre that "it is probably a terrorist act. For us it is an extremely serious act."
He said the museum had received no recent threats and that its staff "are in shock".
Milquet said the government had moved to increase protection at Jewish buildings as well as the Israeli embassy.
Belgium Prime Minister Elio Di Rupo also expressed that he was "very shocked" by the attack.
"All Belgians are united and show solidarity in the face of this odious attack on a Jewish cultural site," he added.