Libyan authorities have arrested at least 50 people in the wake of last week’s killing of US ambassador Chris Stevens in a mob attack in the city of Benghazi, Libya’s parliament chief said Sunday.

Stevens and and three other Americans were killed on Tuesday when suspected Islamic militants fired on the US consulate in the eastern Libyan city with rocket-propelled grenades and set it ablaze.

Megaryef said “a few” of those who joined in the attack were foreigners, who had entered Libya “from different directions, some of them definitely from Mali and Algeria.”