Syrian Kurdish fighters clashed with Turkish forces shelling Kurdish-held towns in northwest Syria on Monday, Kurdish officials said.
A spokesman for the Syrian Kurdish YPG militia in Afrin region, Rojhat Roj, said the Turkish military and Syrian rebels it supports shelled Tal Rifaat, Sheikh Issa and other towns north of Aleppo city.
The bombardment with "artillery and rocket launchers" killed two people and injured seven, he said. Kurdish fighters and allied groups retaliated and firing was continuing.
There was no immediate comment from the Turkish Army.
The Britain-based Syrian Observatory for Human Rights also said the two sides exchanged fire in the area.
The mounting tensions between two U.S. allies in northwest Syria threaten to open another major front in the multi-sided Syrian war.
The head of the YPG told Reuters last week that Turkish military deployments near Kurdish-held areas of northwest Syria amounted to a "declaration of war".
Turkey's Deputy Prime Minister Numan Kurtulmus retorted that his country was not declaring war but that its forces would respond to any hostile move by the YPG.
Rebels said last week that the Turkish deployment aimed to regain control of a string of Arab villages near the border which Kurdish-led militias seized last year.
Turkish policy in northern Syria has focused on countering the growing sway of Kurdish groups which have established autonomous regions since Syria's conflict began in 2011.
Ankara sees the YPG as an extension of the Kurdistan Workers Party (PKK), which has fought an insurgency against the Turkish state for decades
