The Turkish military says its warplanes have hit Kurdish YPG militia targets in the Syrian region of Afrin.
A monitoring group reported seven fighters and two civilians were killed in the strikes on Thursday.
In a statement, the military said 19 targets were destroyed. No more details were given. The state-run Anadolu news agency said the raids began at midnight.
Seven YPG fighters and two civilians died in the strikes, according to the Syrian Observatory for Human Rights. The UK-based group monitors the war in Syria.
Turkish President Recep Tayyip Erdogan and Russian President Vladimir Putin have agreed to strengthen military and security service coordination in Syria, according to the Kremlin.
Ankara launched an air and ground assault on January 20 against the Kurdish YPG militia in the region, which lies on its border.
It opened a new front in Syria's multi-sided, almost seven-year-old war.
Syrian Kurdish fighters and Syrian state media say Turkish forces shelled a primary school, and a water treatment and pumping plant in Syria's northern Afrin region.
YPG spokesman Nouri Mahmoud said Turkey's army and its Syrian insurgent allies hit the main water plant supplying Afrin city, knocking it out of service. He said engineers are trying to repair the damage.
He said shells also hit a primary school in the village of Maydanki a day earlier. There were no casualties.
Syria's state news agency SANA said the bombardment wrecked parts of the school.
The Syrian Observatory for Human Rights said Turkish troops damaged the plant, nine kilometres northeast of Afrin city.
The facility supplies drinking water to hundreds of thousands of residents and displaced people in the wider Afrin region, they added.
What has Ankara said?
A Turkish military source denied the claim, saying: "The Turkish armed forces are not aiming at these kind of targets."
Since the onset of Syria's conflict in 2011, the YPG and its allies have set up three autonomous cantons in the north, including Afrin.
Their territory has expanded since they joined forces with the US to fight ISIL. Washington, however, opposes their autonomy plans as does Syrian President Bashar al-Assad's government.
US support for Kurdish-led forces has infuriated Turkey, which views growing Kurdish power as a security threat along its frontier.
Ankara regards the YPG as a terrorist organisation and an extension of the outlawed Kurdistan Workers Party (PKK) that has waged a three-decade insurgency on Turkish soil.
Former PYD leader speaks to euronews
'Ankara is no different from ISIL'. That is the claim from the former head of Syria's main Kurdish opposition party - one of the most powerful players since war broke out in 2011.
Salih Muslim told Euronews Turkey's Afrin operation is about regaining lost ground.
"It is a kind of revenge with Daesh being defeated in many areas," he said. "So this kind of revenge, I mean Turkey, is forced to do themselves. There is some kind of consensus between the Syrian regime, Iran and Turkey."
Muslim accuses Turkey of links with ISIL, something Ankara has always denied.
"Turkey is not different from Daesh because they have grown up with their help, and they trained them, and even in Afrin now they are using the remains of Daesh who escaped from Raqqa and from Mosu," he added.
Ankara is angered by US support for Kurdish-led forces. Muslim does not fear being abandoned by the US-led coalition.
"The international alliance against Daesh, they are still there, and ethically they should stand beside us. So we dont know what will happen, what they will do If the Turks advance. We will resist for our part. We will resist against this invasion, these attacks, we will resist. The stance of the United States is ok so far. They say 'we are there, we will defend'; I mean there shouldnt be any attacks in Manbij."
Ankara launched a military campaign in neighbouring Syria in a bid to oust ISIL from the border region.
They also want to curb any Kurdish appetite for expansion into Turkish territory.
The PYD's armed affiliate, the YPG, controls swathes of northern Syria.
It says it is not fighting for independence, but to ensure any post-war constitution gives autonomy to regions.