The bombings in Hajjaj village, north of Tikrit, were not immediately claimed, but are similar to attacks carried out in recent months by Daesh (ISIL or ISIS), Reuters reported.
Iraqi security forces retook Tikrit from Daesh in April 2015.
In November, Daesh bomb attacks hit Tikrit, north of the capital, Baghdad, in an apparent diversionary assault as Iraqi forces drove back the terrorists in their stronghold of Mosul.
Daesh overran large areas north and west of Baghdad in 2014, but Iraqi forces have since regained most of the territory they lost.