BAGHDAD, Feb. 20 — In a rare coordinated assault on an American combat outpost north of Baghdad, suicide bombers drove one or more cars loaded with explosives into the compound on Monday, while other insurgents opened fire in the ensuing chaos, according to witnesses and the American military.

Two American soldiers were killed and at least 17 more were wounded.

The brazen attack, which was followed by fierce gun battles and an evacuation of the wounded by American helicopters, was almost surely the work of Sunni militants, most likely Al Qaeda in Mesopotamia, according to American and Iraqi officials. It appeared to be part of a renewed drive by insurgents in recent weeks as more American and Iraqi troops flood the streets of Baghdad and thousands of Marines head to western Anbar Province to try to stem the violence.

Captured documents suggest that insurgents have been able to shoot down more helicopters through coordinated assaults, and hundreds of Iraqis have died in a recent wave of car bombings in Baghdad and elsewhere. American and Iraqi military officials say they are concerned that militants are moving to areas where the American troop presence remains thin.

As the Iraqi government and its American allies struggled to quell the violence and build public trust in the security forces, a Sunni woman caused a furor on Monday when she publicly charged that she had been raped by members of the Iraqi National Police, which is largely made up of Shiites.