Iraqi security forces wrestled control of a provincial council headquarters from gunmen who stormed the building on Tuesday and took hostages.
Police say at least 53 people were killed and nearly 100 injured during the hours-long siege in Tikrit.
Witnesses say the gunmen were wearing military uniforms and suicide vests as they stormed into the building. Investigators say at least one gunman detonated explosives to clear the way for the others to enter.
Officials say a short while later, a car exploded outside of the building, killing a journalist and several law enforcement officers. The gunmen also hurled grenades at law enforcement officials to keep them away.
Local officials say the attackers killed three councilmen inside the building and set their bodies on fire. At least six assailants died during the siege, which some officials have blamed on al-Qaida.
Tikrit, located about 140 kilometers north of Baghdad, is the hometown of the late Iraqi dictator Saddam Hussein.
Some information for this report was provided by AP, AFP and Reuters.