BAGHDAD, Iraq,AP -Nearly 40 people died in a rash of car bombings in Iraq”s capital over a 12-hour span, including two coordinated blasts early Thursday that killed 15 and wounded 28 in a central Baghdad shopping district, police said.

Thursday”s carnage in the capital”s Karradah area came on the heels of bloodshed late Wednesday that included four car bombs exploding within minutes of one another. At least 23 people were killed in western Baghdad”s Shula neighborhood and a nearby suburb. Nineteen were killed in Shula alone.

The attacks served as a chilling reminder of how potent militants remain in the capital despite around-the-clock American and Iraqi troop patrols.

Most residents of Karradah and Shula are from Iraq”s Shiite majority, while the insurgents are almost exclusively Sunni Arabs, a minority that dominated Iraq until Saddam Hussein”s ouster two years ago.

The explosions both days were carried out at times when large crowds were on the capital”s streets. Wednesday night”s bombs came hours before an 11 p.m. curfew, when many residents are out at eateries or chatting on the streets before locking themselves inside their homes.

Thursday”s twin explosions took place when many are just beginning their daily routines. The attacks in Karradah happened nearly simultaneously, police Lt. Col. Salman Abdul Karim and officer Ahmed Hatam al-Sharie said. Five police officers were among the 15 dead.

A young boy, his left leg missing from below the knee, sat on the sidewalk near a mangled bicycle, screaming as a man tried to comfort him. The force of the blasts blew off store shutters, and the surrounding sidewalks were covered with debris, including shattered glass, concrete slabs and charred vegetables and fruit.

A few trees were toppled, scattering leaves on the sidewalk.

Separately, a car bomb detonated by remote control hit an Iraqi police patrol in Tuz Khormato, north of Baghdad, killing one policeman and wounding seven civilians, police Brig. Gen. Sarhad Qadr said. Tuz Khormato is 55 miles south of the northern city of Kirkuk.

In another incident before dawn Thursday, U.S. troops backed by Iraqi troops and helicopters killed seven insurgents who opened fire on the patrol from a home in western Baghdad”s Jamiaa neighborhood, said police Maj. Moussa Abdul Karim and 1st Lt. Mohammed al-Heyaali.

The home was reduced to rubble and U.S. troops standing in front displayed a weapons cache they had seized, including rocket-propelled grenade launchers, machine guns and ammunition.

In all, at least 32 people were killed Wednesday across Iraq, including a prominent Sunni law professor assassinated by gunmen. Jassim al-Issawi was a former judge who put his name forward at one point to join the committee drafting Iraq”s constitution. The assassination appeared aimed at intimidating Sunni Arabs willing to join Iraq”s efforts to create a stable political system.

Al-Issawi”s killing, potentially the most politically significant act of violence since Prime Minister Ibrahim al-Jaafari came to office nearly two months ago, marked the first direct attempt to scare moderates away from political participation.

It sent a powerful message to the Sunni Arab community to either boycott involvement in the fledgling government or risk death.

Insurgents bent on starting a civil war to overthrow Iraq”s U.S.-backed government have maintained nearly eight weeks of relentless attacks, killing more than 1,240 people since April 28, when al-Jaafari announced his Shiite-dominated government.

In Brussels, Belgium, an international conference adopted a declaration of support for the struggling nation, backing the Iraqi government”s &#34efforts to achieve a democratic, pluralist, federal and unified Iraq.&#34

But al-Issawi”s killing and the Baghdad bombings provided fresh evidence of the insurgents” ability to strike with impunity in the heavily protected capital, where U.S. and Iraqi forces hunt insurgents patrol around the clock.

Deputy Prime Minister Ahmad Chalabi, a senior Shiite politician and a former Washington insider, condemned the assassination and renewed his government”s commitment to include Sunni Arabs in drafting the constitution.

Leaders of the Sunni Arab minority also condemned al-Issawi”s assassination, linking it to what they said was a plan to eliminate key minority figures ahead of the crucial task of writing the country”s basic law.

There was no immediate claim of responsibility for al-Issawi”s assassination, but Abu-Musab al-Zarqawi”s al-Qaida in Iraq has threatened to kill Sunni Arabs cooperating with the government or the United States.

Sunni Arabs, who dominated Iraq for decades, lost power when Saddam, their last patron and a Sunni, was ousted. Their boycott of historic elections in January further sidelined them.

But Sunni Arab participation in the political process is essential for Iraq”s passage to democracy.

Parliament has until Aug. 15 to draft the new constitution, which will be put to a referendum two months later. If ratified, it will be the basis for a general election in December, giving Iraq its first, full-term elected government in decades.