Turkey has intensified its shelling of a Kurdish militia in northern Syria, ahead of a threatened ground offensive aimed at driving them out of the area.
The shelling of Afrin region came from Hatay province, Turkish state media said, as troops massed on the border.
The Russian foreign minister has denied reports that Russia is withdrawing its forces from the area.
Turkey has for months said it would clear Kurdish YPG fighters from Afrin, under Kurdish control since 2012.
Turkey regards the YPG as a terrorist group.
Syria has warned against an incursion, threatening to shoot down Turkish jets.
Turkish Defence Minister Nurettin Canikli said the shelling was the "de-facto start" of a planned invasion of Afrin.
The YPG (Syrian Kurdish People's Protection Units) said 70 shells were fired at targets in Afrin overnight.
Rizan Habou, of the Syrian Democratic Council in Afrin, told BBC Arabic that residents were seeking shelter.
"When the villages in Afrin are shelled, the civilians [including] women and children are forced to leave their houses and go to the relatively safer surrounding open space and farmland till the shelling stops," he said.
"The YPG and the civilians will defend Afrin to the last moment."
Turkey's military and intelligence chiefs are in Moscow to try to get Russia's agreement to allow Turkish planes to use the Russian-controlled airspace above Afrin.
Russian consent is essential for any Turkish operation. Moscow is a key ally of Syrian President Bashar al-Assad and has a contingent of soldiers at the airport in the centre of Afrin.
On Friday, the Anadolu news agency reported that Russian military personnel in Afrin were leaving in groups.
But the Russia's Sergei Lavrov later denied the reports.
Turkey has intermittently shelled and carried out air strikes against the YPG in the Afrin area, from where fighters have fired rockets into Turkey.
Ankara sees the militia as an extension of the banned Kurdistan Workers' Party (PKK), which has waged a decades-long insurgency in south-eastern Turkey.
The YPG denies any direct links - an assertion backed by a US-led coalition whose air strikes and special forces have helped the militia and allied Arab fighters drive Islamic State militants (IS) from tens of thousands of square kilometres of Syria.
The Kurdish progress inside Syria has alarmed Turkey.
Turkish President Recep Tayyip Erdogan has repeatedly warned he will not allow a "terror corridor" linking Kurdish-controlled areas along the Syria-Turkish border.
Afrin is currently isolated from two other self-declared Kurdish autonomous cantons - Kobani and Jazira. Turkish-backed rebel forces took over a 100km (60-mile) area separating the territories after driving out IS in 2016.
US support for the SDF has infuriated Turkey, a fellow Nato member.
Ankara recently denounced a US plan to set up an SDF-led 30,000-strong border security force in Kurdish-controlled areas, purportedly to guard against a resurgence of IS.