Police and medical workers said at least 20 Iraqis were killed in clashes early Tuesday in Ramadi, where U.S. ground troops and warplanes have conducted a series of operations over recent days targeting Sunni insurgents.

Ali al-Obaidi, a medic at Ramadi Hospital, said those killed were civilians who died in shelling by U.S. tanks in the Dhubat neighborhood. A police spokesman, speaking on condition of anonymity for fear of reprisals by insurgents, said 20 people were killed, but gave no information about their identities or how they died.

The U.S. military said it had no updated information on Ramadi clashes.

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Insurgents have grown increasingly bold around Ramadi, which lies deep in the Sunni heartland west of Baghdad where tribal leaders were strong allies of former dictator Saddam Hussein.

U.S. forces said they used air-launched weapons on Saturday to destroy a building in the city that had been boobytrapped to explode upon entry. The military said there were no reports of any civilian casualties in that attack.

In other violence, assailants killed seven passengers and wounded two others aboard a minivan ambushed Tuesday near Mandali on the Iranian border, 100 kilometers (60 miles) east of Baghdad, the Diyala provincial police spokesman's office said.

Also in Diyala, two policemen were killed and seven wounded when their patrol was attacked at about 08:30 a.m. 0530 GMT) in a village just outside Muqdadiyah, about 90 kilometers (60 miles) north of Baghdad, the provincial police spokesman said.

Baghdad police spokesman Mohammed Kheyoun said six people had been killed and 14 wounded in fighting overnight between Shiite gunmen and American forces in Shula, northwest Baghdad. Earlier, residents who said U.S. warplanes had fired rockets at homes in the area put the death toll as high as nine. The U.S. military has not commented on the reports.

Elsewhere in Baghdad, one person was killed and four injured when a parked car bomb detonated near a restaurant in al-Hurriyah al-Thanyah in west Baghdad, police Lt. Maitham Abdul-Razzaq said.

Three insurgents were blown apart while attempting to plant a roadside bomb Monday night in a southern suburb of Mosul, 360 kilometers (225 miles) northwest of Baghdad, police Brig. Abdul-Karim Ahmed Khalaf said.

The U.S. military, meanwhile, said an air strike killed three insurgents suspected of being part of a car bomb making ring in Youssifiyah, 20 kilometers (12 miles) south of Baghdad.

Complete coverage is available in FOXNews.com's Iraq Center.