The explosion rocked al-Ataba street, which is packed with medical clinics and shops, on Wednesday. Scores of people were also injured in the blast.
No group has claimed responsibility for the attack, which had the hallmarks of the Daesh Takfiri terrorist group.
The blast comes a week after bomb attacks at a wedding party near Tikrit claimed the lives of at least 26 people.
The northern and western parts of Iraq have been plagued by violence ever since Daesh began an offensive in Iraqi territory in June 2014.
Tikrit, located about 140 kilometers northwest of the capital, Baghdad, was the first Iraqi city to be liberated from the control of Daesh. Iraqi troops retook control of the city in 2015.
Iraqi army soldiers, Hashd al-Sha’abi volunteers and Kurdish forces launched a joint operation on October 17, 2016 to liberate the strategic northern city of Mosul, Daesh’s last urban stronghold in the country.
Earlier this year, the eastern side of Mosul was cleared of terrorists. Iraqi forces are currently fighting to retake the western part.