According to information gathered by Anadolu Agency in Idlib, Turkish artillery units hit PKK/PYD forces from the Reyhanli and Kirikhan dictricts of Turkey's southern province Hatay and a Turkish Armed Forces observation point in Idlib.
Turkish Armed Forces fired at least 36 times during the artillery bombardment in Afrin's Bosoufane, Cindirese, Deir Bellout and Rajo districts.
The Afrin operation follows Turkey's successful seven-month Operation Euphrates Shield, which ended last March.
The PKK/PYD is the Syrian offshoot of the PKK, which is listed as a terrorist organization by Turkey, the U.S. and EU.
Since the PKK launched its terror campaign in 1984, an estimated 40,000 people have been killed in Turkey in related violence.
Following a fragile cease-fire, the group resumed fighting in July 2015. Since then, it has been responsible for the deaths of approximately 1,200 security personnel and civilians, according to an official tally.
President Recep Tayyip Erdogan spoke about the Afrin operation at the provincial congress meeting of his ruling Justice and Development (AK) Party in eastern Elazig province this past week.
"We are destroying the western wing of this corridor with the Idlib operation," Erdogan said.
Erdogan had added that if terrorists in Afrin did not surrender, Turkey would interfere.