U.S. soldiers detained 18 suspected militants in raids targeting roadside bomb networks in the Baghdad area, a day after 14 more American troops were reported killed, most in powerful explosions that struck their armored vehicles.

Iraqis also faced more violence on Friday, the Islamic day of rest. A homicide attacker wearing an explosives vest struck a police patrol in Fallujah, killing two officers and wounding three others, along with six civilians.

The explosion occurred about 11:20 a.m. near a bridge in central Fallujah, a police captain said, speaking on condition of anonymity because he feared retribution.

Fallujah, 40 miles west of Baghdad, was the site of a massive 2004 U.S. military operation, but Al Qaeda in Iraq has regained a presence in the city despite recent U.S. successes in restoring calm elsewhere in Anbar province with the help of Sunni tribes that have turned against the terror network.

The military began another major campaign against Sunni insurgents Monday in the area surrounding Baqouba, the capital of Diyala province, northeast of Baghdad, but an American commander there said a key difference was a new Iraqi commitment to the effort.

"It's different than Fallujah in the fall of '04, because of the Iraqi commitment here. They're side by side with us, and locals have finally realized here that Al Qaeda has no future here," said Brig. Gen. Mick Bednarek, assistant commander for operations with the 25th Infantry Division.

Bednarek estimated several hundred Al Qaeda militants remained in the western half of Baqouba, 35 miles northeast of Baghdad, where fighting continues.

"They're clearly in hiding, no question about it. But they're a hard-line group of fighters who have no intention of leaving, and they want to kill as many coalition and Iraqi security forces as they possibly can," Bednarek told The Associated Press in an interview.

The attack in Fallujah was the latest example of suspected Sunni insurgents fighting other Sunnis who have joined the Iraqi security forces or participated in the political process.

On Thursday, a homicide truck bombing outside the Sulaiman Bek city hall killed at least 17 people, including the mayor, and wounded 66 in a predominantly Sunni area of northern Iraq, officials said.

"The enemy's going to push back, he's going to try and make us look unsuccessful," military spokesman Lt. Col. Christopher Garver said. "We have said it's going to be a long, tough fight over the summer, this is part of that long, tough fight."

Thursday's military announcement of 14 more soldiers killed raised to 15 the number of troops killed since Tuesday, with one death previously announced.

The deadliest attack was a roadside bomb that struck a convoy in northeastern Baghdad on Thursday, killing five U.S. soldiers, three Iraqi civilians and one Iraqi interpreter, the military said. The same day, a rocket-propelled grenade struck a vehicle in northern Baghdad, killing one soldier and wounding three others.

Another powerful roadside bomb killed four U.S. soldiers and wounded another in western Baghdad, and two Marines died in fighting in Anbar province, to the west of the capital. Southwest of Baghdad, two soldiers were killed and four were wounded Tuesday when explosions struck near their vehicle, the military said.

The U.S. military has sought to seize the momentum against Al Qaeda and other militants with the arrival in Iraq of some 30,000 additional troops. It has launched several large-scale operations.

But it has also faced a series of recent attacks on U.S. forces who are more vulnerable as they increasingly take to the streets and remote outposts, and the bombs appear to be growing more powerful. Some U.S. soldiers have reported a recent increase in the use of rocket-propelled grenades.

A British soldier also was wounded Friday when a roadside bomb struck a convoy in the southern port city of Basra, the British military said.

Garver said one of the aims of the latest offensives was to deprive militants of their safe havens where they have been able to assemble huge quantities of explosives.

The military said Friday that U.S. soldiers backed by attack aircraft captured 18 suspected militants and confiscated weapons and equipment the day before in three raids targeting bomb networks around northwestern Baghdad.

Four of the detainees were believed responsible for roadside bomb attacks on a major highway and in other areas near Taji, the site of a U.S. air base 12 miles north of Baghdad, while another was accused of coordinating car bomb attacks against U.S.-led forces west of Taji, according to the military.

"The surge has allowed us to keep an increased presence in the rural area of northwest Baghdad, so we can provide improved security for the people in this region," deputy commander Lt. Col. Peter Andrysiak said in the statement.