Turkish media and officials say the warden of a high-security prison has been shot dead by unknown assailants who fired at his car as it stopped at traffic lights.

The state-run Anadolu Agency says Ismet Akturk, who died in the attack early Tuesday, headed the Kandira prison in northwestern Kocaeli province, which houses people convicted of terror charges or links to criminal gangs. He died in a hospital from his wounds.

The chief prosecutor for the region, Mustafa Kucuk, said the assault appeared to be a "terror" attack, but didn't elaborate.

A banned left-wing group has been blamed for a spate of recent attacks, including taking a prosecutor hostage in an Istanbul courthouse in April. That hostage-taking ended in a shootout with police, which killed the prosecutor.