The attackers killed several merchants and left a car bomb at the scene that detonated when security forces responded to the initial attack in central Baquba, 65 km (40 miles) northeast of Baghdad, an official in the command center said.
The attackers robbed the shops before fleeing, the official said.
Baquba is the capital of Diyala, a troubled province where Al-Qaeda and other Sunni Muslim insurgents still battle Iraqi security forces.
Iraq’s police and army have been on high alert for revenge attacks since US commandos killed Al-Qaeda leader Osama Bin Laden in Pakistan on Monday.
Iraq became a major battleground for the Islamist militant group after the 2003 US-led invasion that ousted Sunni dictator Saddam Hussein.
On Thursday a suicide car bomber killed more than 20 people and wounded 80 at a police headquarters in the mainly Shiite southern city of Hilla. A deputy governor said Al-Qaeda was likely behind the attack.
