Belgian police on Sunday released video footage of the gunman who killed four people in an attack Saturday on the Brussels Jewish Museum.

The man, whose face is concealed under a cap, can be seen in one video entering the building, taking a Kalashnikov automatic rifle from a bag and opening fire on his victims — an Israeli couple, a French woman and a young Belgian man.

A second video shows the man walking outside the museum.

“We call on the whole population to help identify this person,” Deputy prosecutor Ine Van Wymersch said.

She said the gunman “probably acted alone, was armed and well prepared.”

Joel Rubinfeld, head of the Belgian League against anti-Semitism, said Sunday afternoon that the fourth victim in the shooting spree, a young man in his 20s who worked as a receptionist at the museum, had passed away.

Belgium launched a nationwide manhunt Sunday for the lone suspect in the shooting spree.

Forensic experts examine the site of a shooting at the Jewish museum in Brussels, Saturday, May 24, 2014.  (Photo credit: AP/Yves Logghe)

Forensic experts examine the site of a shooting at the Jewish museum in Brussels, Saturday, May 24, 2014. (Photo credit: AP/Yves Logghe)

Interior Minister Joelle Milquet said that the shooter parked a car outside before entering the Jewish Museum in the swanky Sablon area of antique dealers, hip cafes and museums, “fired rather quickly, went outside and left.”

The museum said in a statement that the gunman came in, started shooting at the tourist couple at the entry “and then went on to the reception where he shot the attendant.”

Police had detained one suspect late Saturday but he was soon released and is now considered a witness.

The attack, which came on the eve of national and European Parliament elections, led officials to immediately raise anti-terror measures and protection of Jewish sites.

Van Wymersch said “all options are still open” regarding a motive for the shooting spree. But the government has said it had the hallmarks of an anti-Semitic attack. No one has claimed responsibility for the killings.