Three people were killed and another was seriously injured in a shooting Saturday at the Jewish Museum of Belgium in Brussels, Belgian officials said. A person arrived by car at the museum in central Brussels, entered and quickly opened fire before leaving the scene, Belgian Interior Minister Joelle Milquet told CNN affiliate Bel RTL. The circumstances of the shooting have raised suspicions that it may have been an anti-Semitic attack, but no motive has been determined. The shooter remains at large, and the nation's terror alert level was raised. Belgian public broadcaster RTBF quoted Brussels Mayor Yvan Mayeur as saying those killed were two men and a woman, while a man was seriously injured at the museum, which is near the tourist sites. At a press conference, Milquet said the threat level is highest at locations frequented by the Jewish community. This measure was precautionary, she added.Other news reports, including a BBC News report, indicated that a possible suspect had been detained, but no additional details had been released at the time of this writing (which was Saturday evening).