MOSCOW (Sputnik) — The explosion hit the center of the holy Shiite town in the afternoon, Al-Jazeera said citing its own sources.
There were no immediate claims of responsibility for the attack, the report said.
Karbala is a popular place for pilgrimage among Shiite Muslims as the town is considered to be one of the gates to the Heavenly Paradise promised the faithful in the Quran.
In 2015, some 17 million pilgrims visited Iraqi town of Karbala.