Belgium: Police hunt shooter in Jewish Museum attack - CNN

• Investigators are seeking to identify the suspect in Saturday's shooting


• Images will be released later as police appeal for help to trace the shooter


• Two of those killed are Israeli and the third is French, deputy public prosecutor says


• A fourth victim, a Belgian citizen, is critically injured in the hospital, she says

(CNN) -- Belgian police continued the hunt Sunday for a suspected lone gunman who killed three people and critically injured a fourth in a shooting at the Jewish Museum of Belgium in Brussels a day earlier.

Two of those killed are Israeli and the third is French, deputy public prosecutor Ine Van Wymersch told reporters in Brussels.

Israel's Foreign Ministry said Saturday that the Israelis were a couple in their 50s from Tel Aviv

The seriously injured victim, who is still hospitalized, is Belgian, according to Van Wymersch.

Belgian authorities are planning to release later on Sunday images of the lone suspect who entered the museum and carried out the attack, Van Wymersch said.

Investigators hope the public will help to identify the suspect, who the images show was armed and well prepared, she said.

A person who was detained Saturday soon after the shooting is considered a witness and not a suspect, Van Wymersch added. That witness was not seen in surveillance video recorded during the attack, she said.

The circumstances of the shooting have raised suspicions that it may have been an anti-Semitic attack, but no motive has been determined. Van Wymersch said it was too early to determine whether the attack was an act of terrorism or motivated by anti-Semitism.

On Saturday, Belgian Interior Minister Joelle Milquet told CNN affiliate Bel RTL that a person arrived by car at the museum in central Brussels, entered and quickly opened fire before leaving the scene.

The Interior Ministry raised its terror alert level Saturday in the wake of the attack.

Milquet told a news conference that the security threat level was at its highest at locations frequented by the Jewish community across the country. This measure is precautionary, Milquet added.

CNN's Elwyn Lopez contributed to this report.