Baghdad, Iraq ? A pair of suicide car bombers struck minutes apart Thursday in Baghdad, missing most of the Interior Ministry police they aimed for but killing at least 18 people in the deadliest such attack in more than a month.

The carnage could have been worse. U.S. troops and Iraqi forces later defused a third car bomb that failed to explode, and there were unconfirmed reports of a fourth.

“I was sitting in a minibus with eight other passengers when a white Kia minibus crashed into us suddenly and detonated his vehicle,” said Abdel Ridha Mosa, 43, who was covered in cuts and blood. “I jumped from the window with the woman who was sitting beside me, but the others were completely burned. One was a woman I tried to save but could not.”

Police said at least 36 people, including many women and children, were wounded.

The attack underscored the randomness and unpredictability of an insurgency marked by spikes and lulls in violence. Insurgent attacks are down in recent weeks, and the death toll for American forces has dropped sharply since January and February. But April already has seen at least 54 car bombings, according to U.S. military figures. The past few days have been especially violent.

The Baghdad bombing was just one of several attacks Thursday aimed at Iraqi security forces. Gunmen opened fire on a police station near Kirkuk shortly after dawn and killed five officers and one civilian, police said. The day before, a roadside bomb in Kirkuk killed 12 officers.

U.S. troops detonate a car bomb after it was discovered near a double car bombing in Baghdad, Iraq. Thursday's initial attack killed at least 18 people and wounded three dozen more, but no one was injured in this controlled explosion. The sign at left reads Keep

Insurgents also targeted security forces in Baqouba in central Iraq. An Iraqi intelligence officer was assassinated on his way to work in Baghdad. And in Tikrit, a suicide car bomb exploded outside a U.S. military base, wounding an American soldier, two Iraqi soldiers and several civilians.

The Baghdad bombings hit during the morning rush, within two minutes of each other, and shook the middle-class Karadah district.

A Web site connected with al-Qaida in Iraq, the militant group of Abu Musab al-Zarqawi, claimed responsibility for the blasts. It said the targets were the convoy and a checkpoint guarding Interior Ministry offices where the minister himself, Falah Hassan al-Nakib, was present.