BAGHDAD, Iraq (CNN) -- Seven U.S. troops were killed near Baghdad early Monday in a vehicle rollover accident, U.S. officials said.
U.S. troops question a man who was out after a curfew Sunday night in Baghdad.
Officials do not believe any hostile fire was involved. The location and name of the unit were not available as officials attempted to notify next of kin.
The U.S. military also said that a Task Force Lightning soldier died Sunday from injuries caused by rocket fire during a patrol in the northern Tameem province.
The number of U.S. military deaths in the Iraq war stands at 3,770, including seven civilian employees of the Defense Department.
Also Monday, 12 militants were killed in fighting between troops and insurgents just outside the northern city of Samarra, the U.S. military said.
The military said Iraqi and U.S. troops conducting a helicopter assault raid were confronted by militants from al Qaeda in Iraq. Insurgents fired at troops and wounded three U.S. soldiers, a statement said.
Backed up by helicopters, Iraqi and U.S. ground forces fired back, the statement said, killing 12 people described as "enemy extremists."
Three people were detained and a fourth "was positively identified as a hostage being held for ransom by the insurgents."
Samarra has been the scene of much fighting in recent months. The city in Salaheddin province is the site of Al-Askariya Mosque, the Shiite shrine that was attacked twice, apparently by Sunni militants. Watch U.S. soldiers give a tour of life in Iraq »
The U.S. military also claimed success against militants in volatile Diyala province.
The military said Monday that nine insurgents were killed and 10 detained during an Iraqi and U.S. operation called Operation Lightning Hammer II, which began last week. Soldiers were operating in the Baquba, Muqdadiya and Balad Ruz areas.
"The value of these operations is vital as we continue to pressure and target al Qaeda elements who feel they have a power base in Diyala province," said Lt. Col. James George.
Meanwhile, an official announced a slight easing of security measures in Baghdad during the Muslim holy month of Ramadan, a religious observation that begins this week.
Brig. Gen. Qassim Atta, an Iraqi military spokesman, said on Iraqia TV that the nightly curfew will go into effect at midnight instead of 11 p.m. during Ramadan. It will last until 5 a.m.
The Friday vehicle curfew from 11 a.m. to 3 p.m. will be dropped during the month. But vehicles won't be permitted over many of the Tigris River bridges linking eastern and western Baghdad.
It is unclear what other security measures will be enforced.
Muslims fast during daylight hours during Ramadan. In the evening, they eat small meals and visit with friends and family.
Iraq's prime minister on Monday touted his government's efforts in thwarting "sectarian war" but acknowledged Iraqi troops are not yet ready to take over security duties from the U.S.-led coalition.
"We have succeeded in preventing Iraq from going into sectarian war -- which threatened our dear Iraq -- and I am fully confident that national reconciliation is our only way that takes Iraq into safety in spite of all the destabilizing actions by local and international groups," said Prime Minister Nuri al-Maliki, who addressed the country's parliament, the Council of Representatives.
"Despite the security improvement, we still need more efforts and time in order for our armed forces to be able to take over security control in all Iraqi provinces from the multinational forces that helped us in a great way in fighting terrorism and outlaws" he said.
Al-Maliki's comments came hours before U.S. Gen. David Petraeus and Ryan Crocker, U.S. ambassador to Iraq, were to appear before Congress to deliver reports on military and political progress in Iraq. E-mail to a friend
CNN's Barbara Starr and Mohammed Tawfeeq contributed to this report.