An employee of the Jewish museum of Brussels died of injuries he sustained in the shooting there, bringing the death toll to four people.
The fourth fatality from Saturday afternoon’s shooting passed away later Saturday night, the Benelux broadcaster RTL reported on its website.
The other victims were an Israeli couple, the Israeli foreign minister said, and a female volunteer at the museum.
Belgian police said at a press conference that the shooter arrived in an Audi car to the Jewish Museum of Belgium in central Brussels, entered the building and began selecting targets before he escaped, as did the driver who brought him there.
Police briefly detained a person they initially said was a suspect, but later released him and said they regarded him a witness.
Authorities in Israel and Belgium did not immediately make known the identities of the people killed.