BAGHDAD, Iraq (CNN) -- Two bombings in separate Iraq provinces on Monday killed eight U.S. troops, the U.S. military said.
A boy with a machine gun weeps Monday at the site of a suicide bombing in Kanan that killed a sheik.
A roadside bomb killed three U.S. soldiers and an interpreter in Diyala province, which has been a major front in the war during the "surge" of U.S. troops fighting insurgents near the capital.
Earlier in the day, at least five U.S. soldiers on foot patrol were killed and three others wounded in a suicide bombing in Baghdad.
In addition, suicide bombers killed five Iraqis in two bombings in Diyala province Monday morning, including a sheik who helped battle Sunni extremists and his 5-year-old niece. Watch new suicide tactics in Iraq »
Four U.S. soldiers died at the scene Monday's Baghdad blast and one more died later of wounds, the military said. They were with Multi-National Division-Baghdad. An Iraqi interpreter also was wounded in the explosion, the officials said.
Initial reports indicate the bomber was wearing an explosive vest.
"Five soldiers paid the ultimate sacrifice on behalf of the Iraqi and American people. I ask you remember these fallen heroes and their families as well as their wounded brethren in your thoughts and prayers," said Col. Allen Batschelet, chief of staff for Multi-National Division-Baghdad.
"We remain resolute in our resolve to protect the people of Iraq and kill or capture those who would bring them harm."
The explosion marks the deadliest attack against the U.S. military since five soldiers were killed January 28 in a roadside bombing in Mosul. Troops killed a Saudi insurgent whose network was responsible for that attack.
Earlier, an Iraqi Interior Ministry official said one person was killed and eight people were wounded in a suicide bomb attack targeting a U.S. military convoy in western Baghdad.
It is not clear if the U.S. and Iraqi reports are about the same incident.
Monday's attacks would bring the number of U.S. troops killed in Iraq this month to 10. A total of 3,983 military personnel have died in the nearly 5-year-old war.
The attack came after a bomber near Baquba targeted the leader of a security group assisting U.S. troops.
The teen suicide bomber killed a sheik and a 5-year-old, a day after she went to the sheik's Kanan home claiming to need help finding her husband, police and family members said.
The female suicide bomber, 18, blew herself up at the sheik's home Monday morning, police said. The tribal leader was the head of a local citizens group that has been working with U.S. forces to rout out insurgents. The largely Sunni security groups are known as Awakening Councils.
Kanan is east of Baquba, situated in the volatile Diyala province, which has been a major front for the "surge" of U.S.-led troops targeting militants near Baghdad.
According to one of the sheik's cousins, the teen bomber went to the sheik's house Sunday to ask him for help finding her husband -- thought to be kidnapped or detained. The 18-year-old was told to return Monday, the cousin said.
She returned Monday and staged the attack, killing the sheik, his 5-year-old niece and one of his security guards, police said.
The attack reflects both the growing use of females as suicide bombers in Iraq and the targeting of Awakening Councils, which are also known as Concerned Citizens Groups or Sons of Iraq.
The grass-roots groups, which are sometimes led by former insurgents, have drawn more than 90,000 volunteers to their ranks, military spokesman Rear Adm. Gregory said Sunday.
Since November, there have been at least five attacks carried out by female suicide bombers, including a twin bombing at Baghdad pet markets last month that killed almost 100 people.
Insurgent groups, particularly al Qaeda in Iraq, are increasingly using women as suicide bombers because they are less likely to be searched, the U.S. military has said.
About an hour after the attack at the sheik's home, another suicide bomber approached Iraqi security forces in Muqdadiya and blew himself up as the forces began shooting at him.
The blast killed two civilians and wounded 20 others, including two police officers, authorities said. Muqdadiya also is in Diyala province.
In other developments:
• A suicide car bomb exploded Monday outside an upscale hotel in Sulaimaniya, killing two people and wounding at least 32 others, police said. The blast occurred at the Sulaimani Palace hotel, located in the center of the city. It is in northern Iraq's Kurdish region and is a common stop for visiting government officials, businessmen and contractors.
• Two bombings in Baghdad on Monday killed an Iraqi and wounded nine others, an Interior Ministry official said. A parked car bomb exploded near an outdoor market in Shaab, a Shiite neighborhood in northeastern Baghdad, killing a civilian and wounding seven others. A roadside bomb exploded on a highway near a U.S. military patrol in eastern Baghdad, wounding two bystanders.
• Coalition troops north of Baghdad killed five insurgents and detained 19 people in raids, the U.S. military said Monday. The Sunday raids were part of coalition forces' "untiring efforts to remove al Qaeda from Iraq," said Lt. Col. Maura Gillen, a Multi-National Forces-Iraq spokeswoman.
• Several U.S. troops may have been sickened by dirty water intended for hygiene use and supplied to bases around Iraq between 2004 and 2006, according to a Pentagon report released Monday. However, the Department of Defense inspector general's report points out that because the water was not monitored, it is impossible to tell for sure if it was dirty and if it contributed to the troops getting sick. E-mail to a friend
CNN's Jamie McIntyre, Mohammed Tawfeeq and Jonathan Wald contributed to this report.