BAGHDAD, Iraq (CNN) -- U.S. Army Brig. Gen. Jeffrey Dorko was injured Monday when a roadside bomb exploded near his vehicle in Baghdad, Pentagon sources said.

U.S. Army Brig. Gen. Jeffrey Dorko has been evacuated to Germany, Pentagon sources said.

Dorko is believed to be the highest-ranking U.S. military officer injured in the war. He suffered shrapnel wounds and has been evacuated to Germany, the sources said.

Dorko took command of the U.S. Army Corps of Engineers Gulf Region Division in Baghdad on October 10, according to the Corps of Engineers Web site.

Also on Monday, the Iraqi army freed seven tribal sheikhs abducted Sunday in eastern Baghdad, Baghdad commander Gen. Abboud Qanbar told al-Iraqia state television.

Qanbar said eight sheikhs had been abducted, but one was killed Sunday while resisting.

Earlier, a Diyala tribal leader who is a member of the reconciliation committee in the province said that 11 sheikhs had been kidnapped, eight had been released and three more remained in captivity.

The freed sheikhs were Shiite, from Anbakiya tribe, the tribal leader said. The tribal leader said the body of a Sunni sheikh, who was from the al-Azza tribe, was later found near where the kidnapping took place.

He said the three remaining sheikhs were Sunni.

An Interior Ministry official had originally told CNN that 10 tribal sheikhs -- seven Sunni and three Shiite -- had been kidnapped

Iraqi Defense Ministry spokesman Mohammed al-Askari told CNN that four kidnappers were killed in the raid, which took place in Baghdad's Rusafa district on the Tigris River.

Earlier Monday, the U.S. military blamed the kidnappings on former Mehdi Army militia brigade commander Arkan Hasnawi.

The military said Hasnawi "has joined forces with Iranian-supported special groups that are rejecting [Mehdi Army leader] Muqtada al-Sadr's direction to embrace fellow Iraqis."

Al-Sadr, an Iraqi Shiite cleric who controls the Mehdi Army, has called on the militia to obey a cease-fire following deadly firefights in August with rival Shiite militias.

Iran has denied that Iranian agents are helping train and equip militants in Iraq.

The sheiks were kidnapped while returning home to Baquba after meetings in Baghdad with Iraqi government officials, an Interior Minister official said. The meetings concerned the reconciliation process in the nation.

Cycling suicide bomber kills 28

In Baquba on Monday, a suicide bomber riding a bicycle killed at least 28 Iraqi police at an Iraqi police base, the U.S. military said.

The blast also wounded 17 police officers and three civilians, the military said.

Iraqi police had reported 24 deaths earlier, describing them as police and police recruits. Local health officials put the death toll at 27, with a woman and child among the wounded.

Baquba, the capital of Diyala province, is 32 miles (51 kilometers) northeast of Baghdad.

Akram Salman, 22, a Sunni from Baquba's central Tahrir area told The Associated Press that he was among about 60 recruits when the attack happened.

Al Qaeda in Iraq "has threatened us before and prevented us from joining the police," Salman told the AP. "They slaughtered many policemen, burned their houses, killed their families and blew up their headquarters. Now, when the people have defeated al Qaeda and cooperated with the government, al Qaeda staged this operation to show their presence and to give a message that they are still in control."

Col. David W. Sutherland, commander of U.S.-led coalition forces in Diyala province, said, "This attack is typical of al Qaeda's barbaric and hateful ways, targeting Iraqi security forces who have been working to secure Baquba and enable progress."

North of Baquba, Iraqi police on Monday killed a man attempting to enter a police station and detonate a suicide vest in Hibhib, the U.S. military said. After police killed the man, the vest detonated outside the station, but no one was wounded and no damage was reported, the military said.

Also Monday, a deadly bombing struck about four miles west of Baiji, an Iraqi oil center about 90 miles (145 kilometers) north of Baghdad. The device, placed in a parked car, killed seven civilians and wounded another 15 people, local police said.

In the capital Monday, a bomb in a parked car wounded at least five Iraqi civilians at a bus stop and taxi stand, an Interior Ministry official said. The attack took place in southwestern Baghdad's predominantly Shiite al-Baya'a district, the official said.

Karbala province returns to Iraqi control

In an apparent sign of progress among coalition forces to secure areas south of Baghdad, the U.S. Army handed over responsibility for security of Karbala province to the Iraqi military in a ceremony Monday.

Recent clashes between Shiite factions had delayed the Karbala handover, but the area is now considered to be more peaceful than many other sections of the war-torn country.

During the ceremony at a soccer stadium in the provincial capital, Iraqi Prime Minister Nuri al-Maliki and other dignitaries listened to speeches and watched a parade that ended with a cheerleading-style performance and mock paramilitary drill by Iraq soldiers. Watch al-Maliki and Iraqi forces at the ceremony »

Al-Maliki challenged Iraqi commanders to work on bolstering security forces so they could assume responsibility in more provinces.

"We should all take responsibility for building military capability," the prime minister said.

He added, "Allow me to say that we are late; we are late in building our security forces, and that is for reasons I do not want to talk about here."

The U.S. military said it will maintain a presence in the province to support the Iraqi military.

"Step by step, Iraqis are assuming control for the security in their provinces, and Karbala today is leading the way," said Maj. Gen. Rick Lynch, commander of the U.S. troops in the province. "We are only a phone call away."

Karbala, a Shiite province south of Baghdad, will be the eighth of 18 Iraqi provinces to be handed over to the Iraqi government by coalition forces. The other provinces returned to Iraqi control are Najaf, Muthanna, Thiqar, Maysan, Duhuk, Irbil and Sulaimaniya.

Iraqi security forces are set to assume security responsibility in mid-December for the southern province of Basra, al-Maliki said.



Other developments



Iraqi leaders at a military camp east of Baghdad have given the U.S. military a $1,000 check to aid victims of California's wildfires, a U.S. military official said Monday. "In the months I've been here, I have never been so moved," Army Col. Darel Maxfield, the senior U.S. military official at Camp Besmaya, said in an e-mail. Many of the Marines at that camp are from Camp Pendleton, the U.S. Marine Corps facility north of San Diego that has been the scene of some of the fires.

A battalion of about 800 Kurdish troops moved closer to Iraq's border with Turkey over the weekend, according to U.S. military officials. It was unclear whether Kurdish leaders or Iraq's prime minister requested the peshmerga militia. Iraqi and Kurdish leaders have been under pressure to crack down on the Kurdistan Workers' Party, or PKK, rebels who have triggered a crisis on the northern border with Turkey. Turkish authorities blame the PKK for the recent deaths of dozens of soldiers and civilians and want Iraq to handle the rebels. Turkey has warned that it can't wait indefinitely for Iraq to do so.

E-mail to a friend

CNN's Barbara Starr contributed to this report.

Copyright 2007 CNN. All rights reserved.This material may not be published, broadcast, rewritten, or redistributed. Associated Press contributed to this report.

All About Muqtada al-Sadr • Iraq War