BAGHDAD, Iraq — Two car bombs exploded yesterday only 100 yards from each other during a traffic jam, killing at least 15 Iraqis in the deadliest attack in the capital city since national elections Jan. 30.

The explosions appeared to target an Interior Ministry building and a six-car Iraqi police convoy, but most of those killed were civilians caught in morning traffic. The blast wounded 38 people.

There also were attacks in Baqouba and in Kirkuk, where insurgents launched mortar rounds and fired on an Iraqi police station, killing at least five officers.

Yesterday's violence punctuated several days of escalating attacks in Baghdad. Although U.S. casualties have fallen precipitously since February, Iraqi security forces and government officials have continued to be frequent targets for insurgent fighters.

The violence has disappointed many Iraqis who had hoped national elections and the formation of a government would help stabilize the country.

In statements posted on the Internet, Iraq's al-Qaida branch claimed responsibility for the twin bombs in Baghdad, according to The Associated Press.

The Baghdad bombs exploded along Jamia Street, a busy thoroughfare in southeastern Baghdad. The first thunderous explosion sent up a red pillar of fire that engulfed several cars, shattered windows and shook buildings.

Staccato gunfire crackled through the air as panicked private security guards and government forces stationed at the Interior Ministry facility fired randomly.

Seconds later, another bomb exploded about 100 yards away from the first blast, flinging at least two cars on their sides.

U.S. forces later destroyed a third bomb. Despite the carnage, Iraqi police officers said they were undeterred.

"I will stay a police officer until I lose my life!" said Heider Qassam, 24. "I want to destroy each and every terrorist!"