Tripoli , Libya ( CNN ) -- Six students were wounded when unknown assailants tossed a hand grenade into a school in the eastern Libyan city of Benghazi , hospital staff said Wednesday . The blast occurred during break time at the Mahd al-Maarefa school . In a statement on its Facebook page , Benghazi 's al-Jalaa hospital said it had received the students , some of them between the ages of 13 and 17 . It quoted a student as saying the hand grenade was thrown into the school from outside its walls , injuring students in the legs . Blasts and assassinations are not uncommon in Benghazi , the cradle of Libya 's 2011 uprising and where U.S . Ambassador Christopher Stevens and three other Americans were killed in an attack on the U.S. diplomatic mission in September 2012 . But they have mainly targeted security officials . Attacks on schools are rare . Two and a half years after the fall of Moammar Gadhafi , Libya 's weak authorities are struggling to impose order and control heavily armed former rebels , militias and militants who fought to oust the dictator . Militia brigades often take the law into their own hands as they fight turf wars , and they have refused to lay down their weapons .
Assailants threw a hand grenade into a school in Benghazi . A hospital said the attack happened during school break time . Violence are not uncommon in the eastern Libyan city , but school attacks are rare . Libyan authorities are struggling to maintain order in a country awash with violence .