BAGHDAD, Iraq (AP) – A woman disguised in a man”s robes and headdress slipped into a line of army recruits and detonated explosives strapped to her body, killing at least six recruits and wounding 35, the first known suicide attack by a woman in Iraq”s insurgency.

The attack Wednesday in Tal Afar near the Syrian border appeared aimed at showing that militants could still strike in a town where U.S. and Iraqi offensives drove out insurgents only two weeks ago. A female suicide bomber may have been chosen because she could get through checkpoints, at which women are rarely searched, then don her disguise to join the line of men, Iraqi officials said. Iraq”s most notorious insurgent group, al-Qaeda in Iraq, claimed responsibility for the attack in an Internet statement, saying it was carried out by a &#34blessed sister.&#34

The bombing came a day after U.S. and Iraqi officials announced their forces killed the second-in-command of al-Qaeda in Iraq, Abdullah Abu Azzam, in a raid in Baghdad over the weekend. His death has not slowed insurgent violence, with at least 84 people, including seven U.S. service members, killed in attacks since Sunday.

U.S. President George W. Bush warned violence will increase in the days leading up to a key Oct. 15 referendum on a new constitution, a document that has sharply divided Iraq”s Shiite Muslim majority and the Sunni minority that forms the backbone of the insurgency.

&#34We can expect they”ll do everything in their power to try to stop the march of freedom,&#34 Bush said. &#34And our troops are ready for it.&#34

The U.S. military announced Wednesday that two more American soldiers and an airman were killed in violence and a Marine was killed by a non-combat gunshot. The deaths brought to 1,929 the number of U.S. service members who have died since the Iraq war started in March 2003, according to an Associated Press count.

In the holy city of Najaf, south of Baghdad, an attacker set off an explosion in the home of a bodyguard of radical Shiite cleric Moqtada al-Sadr on Wednesday, killing two people and wounding five, al-Sadr aides and a hospital official said.

In the attack at the Tal Afar army recruitment center, the female suicide bomber was wearing a traditional white &#34dishdasha&#34 robe and a checkered kaffiya headscarf, both worn only by men, to blend in with the line of Iraqi applicants, Maj. Jamil Mohammed Saleh said.

She detonated explosives packed with metal balls and hidden under her clothes, Saleh said. Six recruits were killed and 35 wounded, said hospital officials in Tal Afar, 260 miles northwest of Baghdad.

In a photo of the attacker”s head taken by Saleh and shown to AP, the woman appeared to be in her early 20s with dark eyes, light skin and brownish hair. Saleh said it was not known whether she was Iraqi.

U.S. and Iraqi troops swept through Tal Afar in a Sept. 8-12 offensive, with Iraqi authorities claiming nearly 200 suspected militants were killed and 315 captured, though many of the insurgents in the town escaped. Since then the bulk of the forces participating in the offensive withdrew, though a U.S. base remains.

It was the first known time that a woman has succeeded in carrying out a suicide bombing in Iraq since the insurgency began, though it was not the first attempt.

In March, four women, reportedly sent by the insurgent group Islamic Army in Iraq, were caught in a town south of the capital before they could set off explosives belts they were wearing. In the last days of Saddam Hussein”s regime, just before the April 2003 fall of Baghdad, two women detonated their car near the city of Haditha, killing three American soldiers.

Gen. Ahmed Mohammed Khalaf, the regional police chief, said insurgents were exploiting the fact that women are not searched at checkpoints &#34because of religious and social traditions.&#34

Women and children will now be searched at Tal Afar checkpoints, he said.

Still, the attack raised the prospect of more women bombers being used by the insurgency, a tactic difficult to defend against, especially during the referendum. Men and women turned out in large numbers to vote in parts of Iraq during January parliamentary elections, and images of veiled women flashing their ink-stained fingers after voting became an iconic symbol of hopes for democracy.

Maj. Gen. Hussein Ali Kamal, intelligence head at the Iraqi Interior Ministry, said the Tal Afar attack &#34rings danger alarms&#34 and requires new techniques, including increased searches of women at sensitive locations. &#34But this will be a problem, because women are taking part in our new political life and finding large numbers of female security officers to search them is not an easy process,&#34 he told AP.

In the past, women have played only a supportive role in the insurgency, helping smuggle equipment or feed, shelter and give medical treatment to fighters, said Nora Bensahel, an insurgency expert with Rand Corp., a nonprofit research group based in Santa Monica, California.

&#34This could be a sign that the insurgency is getting greater support among a larger segment of the population, that women are getting more militant and willing to take on a greater role,&#34 Bensahel said. &#34It could also be a sign that the insurgents are having trouble finding male recruits.&#34