Gunfire from the Isis-held area of Syria just across the border with Turkey has killed a Turkish officer and wounded another five soldiers in the southern province of Kilis on 23 July.
The area is where elite troops of the Turkish armed forces were been deployed earlier this week.
The Maroon Berets were deployed in areas close to the border with Syria, which are held by IS.
The Kilis governorate declared two areas close to the Syrian border as "special security zones" for five days.
Unconfirmed reports say that Turkish army started a military operation against IS and clashes were taking place in the area after the soldier was killed.
Anadolu news agency reported that Turkish forces returned fire and killed an IS militant.
According to NTV, Turkish tanks were pounding the jihadist group across from the Turkish Elbeyli border village.
Radikal news site reported that F-16 fighter jets have taken off from Turkish air base in Diyarbakır.
If confirmed, the exchange of fire would represent the first direct gunfight between IS and the Turkish forces.
Earlier this week, a suicide bombing in the south-eastern town of Suruc killed 32 young aid workers and socialists who were preparing a summer aid mission for the war-torn Syrian town of Kobane, just over the border.
The alleged bomber had been identified as a 20-year-old Turkish student called Seyh Abdurrahman Alagoz, from Adiyaman, in south-eastern Turkey.
Prime Minister Ahmet Davutoglu said "Daesh", the Arabic acronym for the Islamic State (Isis), was responsible for the attack and the young assailant had links with the jihadist group.