The Turkish army announced on Thursday night that it would retaliate with artillery fire at Syrian government targets in Syria, after an air strike killed 29 Turkish soldiers in the northwestern Idlib province, France24 reports.

"All known" Syrian government targets are under fire by Turkish air and land support units, Turkey's communications director Fahrettin Altun said, adding that Turkey has decided to "respond in kind" to the attack by the Syrian government.

The remarks came immediately after an air strike by Syrian regime forces against Turkish military in Idlib.

While the governor of Hatay, which sits on the border with Syria, said 29 soldiers were killed in the air strike, the Syrian Observatory for Human Rights gave a higher death toll and said 34 Turkish soldiers were killed.

After the attack, Turkish President Recep Tayyip Erdogan held an extraordinary meeting on the situation in Idlib at his presidential complex in Ankara, attended by ministers and military officials.

Meanwhile, the State Department said the United States is very concerned about the attack on Turkish soldiers in Syria’s Idlib region and stands by its NATO ally Turkey.

“We stand by our NATO Ally Turkey and continue to call for an immediate end to this despicable offensive by the Assad regime, Russia, and Iranian-backed forces,” a State Department representative said in a statement.

Syrian President Bashar Al-Assad's forces have pushed hard in recent months to retake Idlib, which is the last large rebel-held region in northwestern Syria.