BAGHDAD (AP) — Iraqi security officials say a series of explosions in the northern city of Kirkuk has killed at least four people and wounded 23.

The officials said the six blasts went off in quick succession Thursday night after iftar, the meal that breaks daylong fasting during the Muslim holy month of Ramadan. They struck center of the city when streets are typically crowded.

The nature of the blasts was not immediately clear, but the officials said they appeared to be improvised explosive devices. The officials spoke on condition of anonymity in line with regulations.

Iraq declared victory against the Islamic State group in 2017, but the group continues to carry out attacks through sleeper cells, particularly in the country's north.