"Unknown gunmen on Sunday night opened fire against two vehicles with a number of journalists onboard on the Kirkuk-Riyadh road near Houd 18 village in southwestern Kirkuk," the source, who preferred not to be named, told the independent news agency Voices of Iraq (VOI).
"Three journalists, working for al-Watan newspaper, were killed and two of their companions were injured in the attack," he added.
Police forces sealed off the area and opened investigation into the incident.
"The dead men are: Jasem Mohammad Noufan, Khaled Mohammad Noufan and Ziyad Tareq," the source highlighted.
"The bodies were sent to the forensic medicine department, while the wounded rushed to a nearby hospital for treatment," he said.
Kirkuk is 250 km northeast of Baghdad.