BAGHDAD - A wave of bombings killed at least 72 people in Baghdad Thursday, the first attacks since Iraq's Shi'ite-led government was engulfed in a crisis that risks fracturing the country along sectarian and ethnic lines.

Iraqi security forces inspect the site of the bomb attack in Baghdad's Shaab District, northern Baghdad, December 22, 2011. [Photo/Agencies]

The bombings, just days after the last US troops left Iraq, marked a violent backlash against Shi'ite Prime Minister Nuri al-Maliki's move to sideline two Sunni rivals. The tensions threaten a relapse into the kind of sectarian bloodletting that drove Iraq to the brink of civil war a few years ago.

At least 18 people were killed when a suicide bomber driving an ambulance detonated the vehicle near a government office in Baghdad's mostly Shi'ite Karrada district, sending up a huge smoke cloud and scattering car parts into a kindergarten, according to police and health officials.

"We heard the sound of a car driving, then car brakes, then a huge explosion. All our windows and doors are blown out, black smoke filled our apartment," said Maysoun Kamal, who lives in a Karrada compound.

Police and security sources said there were more than 10 explosions across Baghdad, mostly targeting Shi'ite districts. A total of 217 people were wounded.