Daesh (also known as ISIL or ISIS) group claimed it had shot down an Iraqi military plane in the area, killing five crew members.
The military source said authorities had launched a search for the crew after the Cessna 208 Caravan went down near Kirkuk, around 220 kilometres (135 miles) north of Baghdad, AFP reported.
In a statement on Twitter, ISIL said it had shot down a military plane with anti-aircraft artillery and that it been on a bombing run against the city of Hawija, a stronghold of the militants in Kirkuk province.
Iraqi forces have been making gains against ISIL in recent months as they seek to reclaim territory seized by the group during a major offensive in 2014.