The headquarters of al-Qaeda-linked jihadist group, the Islamic State of Iraq and the Levant (ISIL) , in the main northern city of Aleppo has been seized by fighters from several Syrian rebel brigades.
“Fighters from several Islamist rebel brigades took control of the children's hospital in the Qadi Askar district, which is the headquarters of the Islamic State of Iraq and the Levant in the city,” the Syrian Observatory for Human Rights said.
ISIL on Tuesday urged its fighters to “crush” other rebel groups in Syria,  in an audio message from the group’s spokesman.
ISIL’s threat came hours after a rival al-Qaeda group said it has joined forces with other rebel groups in fighting ISIL.
Al-Nusra Front leader Abu Mohammad al-Golani said in an audio recording that “high-level” fighting erupted between his group and ISIL on Tuesday. 
He blamed the fighting on what he said were “mistakes” made by ISIL, such as the arrest of a Nusra commander in Raqqa.
In his message, Golani urged all rebel groups to unite against President Bashar al-Assad regime.
“This unfortunate situation prompted us to make this initiative to save the ground from loss. This initiative calls for the formation of a legitimate committee from all recognized factions with an independent leadership,” he said.
Golani also noted that all infighting in the groups must end and an exchange of prisoners should take place, adding that rebels should focus their efforts on fighting Assad’s forces and not fighting each other.