Added GIs Patrol Baghdad

U.S. soldiers sent to beef up security in Iraq’s capital were seen for the first time on the city’s streets Saturday as Iraqi police used loudspeakers to reassure people that the Americans were there to protect them.

But at least 21 people were killed or found dead, most of them in Baghdad, which is being racked by bombings and sectarian slayings. The dead included a Shiite couple and their two daughters abducted earlier in the day in Baghdad’s mostly Sunni area of Dora, police said.

With Sunni-Shiite killings on the rise, about 3,700 soldiers of the Army’s 172nd Stryker Brigade were brought from northern Iraq to bolster U.S. and Iraqi security forces that have struggled to contain the violence.

Several Stryker armored vehicles took positions in the mostly Sunni district of Ghazaliya, one of the city’s most dangerous areas. Police used loudspeakers to encourage residents to reopen shops and go about their business because the soldiers would protect them.

U.S. commanders said they hoped the presence of heavily armed American troops would intimidate sectarian death squads believed behind many of the killings and reassure Iraqis -- especially Sunni Arabs -- that they would be protected by Iraq’s predominantly Shiite security forces.

Moving the Stryker Brigade to Baghdad, however, meant drawing down -- at least temporarily -- the U.S. military presence in northern Iraq. The brigade, based in Mosul, had subordinate units scattered over a wide area, including routes used by foreign militants slipping in from Syria.

Fears of trouble in the north rose Friday when a car bomb killed a police colonel in Mosul, triggering a firefight between police and insurgents. Iraq’s Defense Ministry and police announced that 55 suspected insurgents had been captured around Mosul after the violence.

A curfew remained in effect for a second day in the eastern part of Mosul while police searched for insurgents.

The U.S. command said it thought the risk of moving the Stryker Brigade was worth taking because of the situation in Baghdad, where tensions are high. Sectarian bloodshed has soared in the capital since the Feb. 22 bombing of a Shiite shrine in Samarra, which triggered reprisal attacks on Sunnis.