A car bomb exploded in central Baghdad and a suicide bomber blew himself up among police and civilians who rushed to help the wounded, killing at least 25 people and wounding 48 in the double strike, according to TVNZ.
The double bombing took place in the Kasra neighbourhood on the east bank of the Tigris River.
Police said the death toll could rise further.
The bombing was one of the deadliest in Iraq in months.
Violence in Iraq has decreased dramatically over the past year and militants no longer control whole swathes of its towns and villages.
Bomb attacks on civilian and military targets occur daily, but such massive strikes are rare.