BAGHDAD (AP) — Two suicide bombers targeted Iraqi police checkpoints in commercial areas in central Baghdad during rush hour Thursday, killing at least 21 people, officials said. The Islamic State group swiftly claimed responsibility for the blasts.

Both attacks were carried out by bombers on foot, wearing explosives-laden vests, two police officers said. One bomber struck in Baghdad's Bab al-Sharji area, killing nine civilians and three police officers there. Forty-five people were wounded in that explosion.

The second bomber hit in al-Wathba Square, killing nine people, including four policemen, and wounding 31.

Two medical officials confirmed the casualty figures. All officials spoke on condition of anonymity because they are not authorized to talk to reporters.

Iraq is going through its worst crisis since the 2011 withdrawal of U.S. troops. The Islamic State group controls large swaths of the country's north and west after capturing Iraq's second-largest city of Mosul and the majority of the western Anbar province last year.

In a statement posted on its Twitter accounts, the Islamic State group claimed responsibility for the attacks, saying it targeted police and Shiite paramilitary forces. The Associated Press could not immediately verify the authenticity of the statement, but its language and phrasing is consistent with past IS claims of responsibility.

Following its blitz last year, the IS — which splintered off from Iraq's al-Qaida branch — now holds about a third of Iraq and neighboring Syria in its self-declared "caliphate."

Since the emergence of IS extremists, Baghdad has seen near-daily attacks, with roadside bombs, suicide blasts and assassinations targeting Iraqi forces and government officials, with significant casualties among the civilian population.

The violence has killed hundreds and displaced tens of thousands of Iraqis.

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Associated Press writer Murtada Faraj in Baghdad contributed to this report.