The Islamic State terror group claimed responsibility Tuesday for a back-to-back twin bombing at an outdoor market in Baghdad, part of a series of attacks that left at least 69 dead across the Iraqi capital.

The deadliest attack unfolded in the Shiite-dominated northern Shaab neighborhood, killing 34.

Police told The Associated Press the Shaab attack started with a roadside bomb explosion outside the concrete blast walls surrounding the open-air market. Afterwards, they said a suicide bomber blew himself up as people gathered to help the victims of the first explosion. At least 75 others were wounded.

In an online statement, ISIS claimed the attack was carried out by an Iraqi and targeted members of Shiite militias. The Associated Press could not verify the authenticity of the statement but it was posted on a militant website commonly used by extremists.

Shortly after the Shaab attack, a parked car bomb struck a fruit-and-vegetable market in the Shiite-dominated neighborhood of Dora, in southern Baghdad, killing eight people and wounding 22 others, a police officer said.

In Baghdad's sprawling eastern Shiite district of Sadr City, a suicide car bombing hit a crowded outdoor market, killing 18 people and wounding 35 others. In northeast Baghdad, a suicide bomber targeted a restaurant in the Habibiya neighborhood, killing nine and wounding 18.

Medical officials confirmed the casualty figures. All officials spoke to The Associated Press on condition of anonymity as they were not authorized to talk to reporters.

Commercial and public places in Shiite-dominated areas are among the most frequent targets for the Sunni militants seeking to undermine the Iraqi government efforts to maintain security inside the capital. But the Islamic State has not confined its latest attacks only to Baghdad.

A wave of bombings in and around Baghdad over the past week has killed almost 200 people.

Iraqi oil workers resumed work Tuesday at a natural gas plant north of Baghdad, two days after a coordinated ISIS dawn assault left at least 14 people dead there, a senior Oil Ministry official said.

Sunday's attack in the town of Taji, about 12 miles north of Baghdad, saw a suicide car bombing at the facility's main gate, followed by several ISIS fighters breaking into the plant where they fought with security forces for hours before the attackers were repelled.

The dead included six civilians and eight security forces while 27 Iraqi troops were wounded. Closed-circuit television images showed an explosion that sent thick black smoke rising above the plant. As flames engulfed the facility and nearby palm trees, pedestrians were seen running for cover. The top of one of the gas-processing units was blown off.

It took hours before Iraqi troops repelled the attackers.

On Tuesday, work at the plant's three production lines returned "to normal levels," said Deputy Oil Minister Hamid Younis.

The plant was back to full capacity of producing 30,000 cooking gas cylinders a day, he said, adding that Sunday's attack had only damaged two gas storages and a few pipelines. Iraqi state TV showed workers in navy blue overalls filling metal and plastic cylinders on conveyor belts and forklift trucks loading cylinders into trucks.

The Associated Press contributed to this report.