BAGHDAD- Four people were killed and another 17 wounded in a car bomb attack on Thursday in the sprawling Sadr City district of Baghdad, Iraqi police and medical sources said.

The car was parked at a busy second-hand equipment market in the mainly Shi'ite Muslim district, police said.

An Iraqi military statement said the blast, targeting an eastern Baghdad market, had killed one civilian, wounded 12 others and set several vehicles on fire.

Black smoke was rising from the market place and ambulances rushed to save the wounded, said Reuters witnesses. Police cordoned off the site of the blast shortly afterwards.

There was no immediate claim of responsibility for the attack. It was the second major deadly bombing to hit Baghdad this year after a suicide attack claimed by Islamic State militants killed at least 32 people in a crowded market in January.

Large bomb attacks, once an almost daily occurrence in the Iraqi capital, have halted in recent years since Islamic State fighters were defeated in 2017, part of an overall improvement in security that has brought normal life back to Baghdad.

The January blast was the most deadly in three years.

Thursday's attack comes during an election year, a time when tension between rival Iraqi political groups has often caused violence.

The populist cleric Moqtada al-Sadr, after whom Sadr city is named and who commands a following of millions of Iraqis, counts among his enemies both Islamic State and rival Shi'ite parties with militias backed by Iran.

On Wednesday, separate violence linked to regional rivalries saw an explosives-laden drone target U.S. forces at Iraq's Erbil airport in northern Iraq and a separate rocket attack kill a Turkish soldier at a military base nearby. 

(Reporting by Baghdad newsroom; Editing by John Davison, Toby Chopra and Gareth Jones) ((ahmed.rasheed@thomsonreuters.com; +964-7901-947-131; Reuters Messaging: ahmed.rasheed.thomsonreuters.com@thomsonreuters.net))