Turkish defence ministry says the attack also wounded nine soldiers, one of them critically.
The attack on Monday also left nine soldiers wounded, one of them seriously.
The ministry said Turkish forces retaliated against the attack and destroyed targets in the Idlib region, the last rebel-held stronghold in war-torn Syria.
It added that the Syrian forces carried out the shelling despite being previously notified of the positions of Turkish forces.
The development came a day after a large Turkish military convoy moved into the area on Sunday amid a new Syrian government offensive.
The Turkish military convoy consisted of dozens of armoured vehicles, fuel tanker trucks and flatbed trucks carrying tanks and armoured personnel carriers.
Al Jazeera’s Sinem Koseoglu, reporting from Istanbul, said Turkey sent the reinforcements to establish a military post and observation post around the Saraqib area.
“As the Syrian government advanced from south to north in Idlib, three of the 12 Turkish military observation posts are currently being surrounded by Syrian government forces,” she said.
“And the displacement is ongoing. That’s why the aim of the new military post was to stop the Syrian government advance towards Aleppo.”
She said: “It seems the Syrian government is now trying to push the opposition for a military solution rather than a political one.”
Displaced by violence
Idlib province is home to about three million people, many of them displaced from other parts of Syria in earlier bouts of violence.
According to the United Nations, almost 390,000 people, mainly women and children, had fled their homes in northwestern Syria since December 1 last year.
Turkey has set up its military posts around Idlib in line with the 2018 deal between Russia, Iran and Turkey for de-escalation zones in the region.
The Hay’et Tahrir al-Sham armed group, a former al-Qaeda affiliate that is considered by Russia and Turkey a “terrorist” organisation, controls a large portion of Idlib.
Russia and Turkey cooperated late last year in establishing the borders of a so-called safe-zone in a separate region in northeastern Syria, following an operation against Kurdish fighters dubbed “terrorists” by Ankara.