BAGHDAD, Iraq — A female suicide bomber disguised in traditional male robes killed seven people and wounded at least 35 when she detonated explosives outside a police recruitment center in the troubled northwestern city of Tal Afar yesterday, according to Iraqi authorities.

The bomber was believed to be the first female to carry out a deadly suicide attack in Iraq since U.S.-led troops ousted Iraq President Saddam Hussein in April 2003, and locals met the news with a weary sense of inevitability brought on by the continuing insurgent violence.

While female suicide bombers have struck repeatedly in Israel, Russia and Chechnya, there have been few such attacks in Iraq. Before the fall of Baghdad almost 2 ½ years ago, two women killed three American soldiers when they blew up their car at a checkpoint near the city of Haditha. A woman was caught carrying explosives as she was about to enter a government building in Baghdad six months later.

Iraq's most notorious insurgent group, al-Qaida in Iraq, claimed responsibility for the attack in an Internet statement, saying it was carried out by a "blessed sister."

"I am not surprised to hear this news," said Abed Hazzem, a police officer in Baghdad. "We are on the lookout for anything. They've used dogs, donkeys, poisoned food, and now women."

The unusual attack came amid another series of bloody episodes across Iraq.

Near the city of Safwan in southern Iraq, two American convoys struck roadside bombs within the same hour yesterday, killing two soldiers and an airman. Another soldier, assigned to the 2nd Marine Division, II Marine Expeditionary Force, died Tuesday after he was shot during combat in Ramadi, officials said.

Insurgents have stepped up their bloody campaign after a joint U.S.-Iraq military offensive in Tal Afar near the Syrian border earlier this month. The violence has mostly targeted Shiites. But in recent months, there have also been reports of police abuses against Sunnis.

In Tal Afar, residents have slowly begun returning to a community patrolled by soldiers and riddled with checkpoints, sandbags and barbed wire.

Human error blamed for fatal copter crash

SAN DIEGO — A helicopter crash in western Iraq in January that killed 30 Marines and a sailor, the deadliest crash in more than two years of combat in Iraq, resulted from human error, not mechanical failure or hostile fire, according to an investigative report released yesterday by the Marine Corps.

The crew of the Super Stallion became disoriented when weather turned bad and visibility was quickly reduced and flew the helicopter into the ground. The crew apparently did not realize that the helicopter had begun banking to the left rather than flying straight, according to the report.

The helicopter was taking troops to western Iraq to help protect polling places during the Iraqi election when it crashed in the desert on the night of Jan. 26. A second helicopter made the trip safely.

The pilot of the second helicopter, Capt. Norman T. Day, whose responsibility included providing updated weather information for both crews, has been taken off flying status, the report said. According to the report, Day did not provide such information to the doomed helicopter crew.