Al-Qaeda-linked militants are battling an IS affiliate in eastern Libya after one of their leaders was shot dead by masked gunmen. Nasr Akr, an Al-Qaeda-inspired militant once jailed in the U.K. on terrorism charges, was assassinated along with his aide in the eastern town of Darna, home to many of Libya's veteran jihadis. Akr's group, known as the Shura Council of Darna's Jihadis, announced his killing in a statement Wednesday, blaming it on ISIS militants and vowing retaliation. Akr's killing sparked heavy fighting, leaving at least nine ISIS militants dead, witnesses said. ISIS seized control of Darna last year. ISIS began as an Al-Qaeda affiliate but later had a bitter falling out with the global jihadi network. The two groups have also clashed in Syria.