The sticky bomb was attached to the vehicle of traffic police near the Money Exchanger’s market in the city.
The blast happened at around 4:30 on Sunday afternoon.
Immediately, the provincial police spokesman, Abdul Ahad Walizada, confirmed the incident but said it had no casualties.
However, Arif Jalali, Chief Physician at Herat Regional Hospital said that nine wounded people have been taken to the hospital so far.
He said the health condition of two victims including a child were critical.
No individual or group has claimed responsibility for the attack.