Sedat Gezer, the coach of Black Sea side Bafraspor, died of wounds in hospital soon after gunmen burst into the club and opened fire while goalkeeping coach Ismail Kurt died at the scene.
Bafraspors manager Engin Ozarslan was also wounded in the attack.
The identity of the gunmen and their motive for the shootings is still unknown. Police are investigating.
Bafraspor is currently 14th in its group, third from last, with seven wins from its 24 games played so far this season.