BAGHDAD - At least five people were killed and more than 20 wounded in three bomb attacks in Iraq's holy Shi' ite city of Karbala in south of Baghdad on Sunday, the police said.

"We have five people killed and more than 20 wounded by the three blasts of Karbala," an Interior Ministry source told Xinhua on condition of anonymity.

Two blasts were caused by bombs attached to cars parking outside the passport and identity card office in central Karbala, some 110 km south of Baghdad, the source said.

Another roadside bomb explosion struck the reinforcement troops rushed to the scene of the first two blasts, the source added.

The death toll could rise as many of the victims were evacuated to several hospitals and medical centers in the city, he said.

Sporadic attacks are still common in Iraqi cities despite the dramatic decrease of violence over the past few years.