On Friday, the explosion hit the minibus in Karbala, leaving 12 people killed and five more injured.
"The national security forces detained [suspected] perpetrator of the explosion in Karbala," a source in the security forces told al-Sumaria broadcaster on late Friday.
According to the source, the suspect was detained in a restaurant not far from the site of the attack.
No group has claimed responsibility for the attack yet. The situation in Iraq has been highly unstable for years due to activities of the Daesh* terror group, which lost all the territories previously seized in the country but continues to stage attacks across the Arab nation.
*Daesh (ISIL/ISIS/Islamic State/IS), a terrorist group banned in Russia and a wide number of other countries.