Earlier in the day, the supporters of Iraqi Shiite cleric Moqtada Sadr took to the streets calling for election reforms and anti-corruption measures, and clashed with police near the district where government buildings are located.
One of those killed was a serviceman of the Iraqi police.
The demonstrators reportedly carried cut-and-thrust weapons and firearms.
Sadr called on his supporters to calm down, criticizing the excessive use of force, while Iraqi Prime Minister Haider Abadi called on citizens not to violate law and stressed that they were not deprived of the right to conduct peaceful demonstrations.