Serbian police said on Wednesday that an unidentified assailant attacked a guard with knives outside the Israeli Embassy in Belgrade and was killed just after midnight.

Interior Minister Ivica Dacic said that police were treating the incident as a “terrorist attack” and had raised the terror threat to the highest level and stepped up police presence at key locations.

Dacic said that “a minor, so far unidentified … shouting Allahu Akbar, attacked the member of Gendarmerie and attacked him with two knives.” He added that the police officer “liquidated” the assailant in “self-defense” and was lightly wounded.

Dacic said that Serbia's security agencies had been monitoring the attacker, who he said was a supporter of the Islamic State group.…