According to reports, a bomb planted on a bus went off as the vehicle left a terminal. The explosion took place in close vicinity of the governor's office, the reports said.
Meanwhile, Britain-based Syrian Observatory for Human Rights chief Abdel Rahman said three people were killed and nine others were injured.
"The explosion is the result of a bomb that was placed in a bus in the centre of Afrin," Abdel Rahman said.
It was not immediately clear who was behind the blast.