Turkish officials say a soldier has been killed and three others were wounded in an attack by Syrian Kurdish militants in a Turkish-controlled region in northern Syria.

Turkey's Defense Ministry says Tuesday the attack by the Syrian Kurdish People's Protection Units, or YPG, occurred in the so-called "Euphrates Shield region," which Turkey and Turkish-allied Syrian opposition forces cleared of Islamic State militants in a cross-border operation in 2016.

The ministry did not provide further details but said Turkey's military responded to the attack by striking at YPG targets in the area. Pro-Kurdish media said Turkish troops retaliated by shelling. It was not immediately known if the retaliatory strikes resulted in casualties.

Turkey considers the YPG to be an extension of outlawed Kurdish rebels fighting inside Turkey.