Diyarbakir - One man and a 15-year-old boy were killed when they were hit by stray bullets from Syria in the Turkish border town of Ceylanpinar, Turkish security sources and health officials said on Wednesday.
The incident, which happened on Tuesday, was the most serious spillover of violence into Turkey in weeks and highlights the growing concern that Syria's civil war is dragging in neighbouring states.
The bullets came from the adjacent Syrian town of Ras-al Ain, where Kurdish fighters have been battling Islamist anti-government rebels since Tuesday. Ceylanpinar, in southeastern Sanliurfa province, sits just across the border from Ras al-Ain.
Health officials earlier said the boy was undergoing surgery after being hit in the head by a bullet but later confirmed he had died of his wounds on Wednesday. Security sources said clashes were still ongoing.
The Syrian Observatory for Human Rights, a group opposed to Syrian President Bashar Assad, said Kurdish armed men had taken control of most of Ras al-Ain from Islamist rebel fighters from the al-Qaeda-linked Nusra Front.
52 killed in bombing
The clashes between Kurdish fighters, who generally support the creation of an autonomous region within Syria, and Islamist Arabs started on Tuesday after Nusra fighters attacked a Kurdish patrol and took a gunman hostage, the Observatory said.
Clashes between Kurds affiliated with the Democratic Union Party (PYD), a Syrian Kurdish party with links to Kurdish militants in Turkey, and anti-Assad Syrian and foreign fighters have erupted since Kurds began asserting control over parts of the northeast from late last year.
Ras al-Ain, also known by its Kurdish name Serekani, and Ceylanpinar were once a single town under the Ottoman Empire before they were split after World War One, and both have Arab and Kurdish communities.
In the worst example of the spillover of violence into Turkey, 52 people were killed when twin car bombs ripped through Reyhanli, another border town, on 11 May. Turkey accused Syria of involvement in the attacks but Damascus has denied any role.
Turkey, which is sheltering around 500 000 Syrian refugees, has become one of Assad's most vocal critics and has scrambled war planes along the border as stray gunfire and shelling hit its soil. The civil war began with anti-government protests in March 2011.