A suicide bomber blew up his truck near a central Baghdad market on Saturday in Iraq's deadliest attack so far this year, killing at least 102 people just ahead of the nighttime curfew.
Another 215 people were wounded in the grisly attack in Baghdad's Al-Sadriya district, security and medical sources said.
The bombing was the worst attack in 2007 and the second biggest since multiple Sadr City car bombings last November killed more than 200 people in northeastern Baghdad.
"A suicide truck bomb exploded near the Sadriya market, in central Baghdad on the east bank of the Tigris River. At least 102 people were killed and 215 wounded," a security source said.
The blast sent a long plume of thick grey smoke into the overcast sky just before dusk, when markets are usually crowded with shoppers out for food ahead of the nighttime curfew between 9 pm and 6 am.
An AFP photographer said terrified survivors threw stones at police who had cordoned off the area and prevented ambulances from reaching the site owing to rumours that there was another bomb in an ambulance.
Police transported the victims in all available police vehicles, but one policeman who was trying to evacuate wounded in his blood spattered pick-up truck was beaten by
Ambulances, fire lorries and police pick-ups raced as close to the scene as possible, their red and blue lights flashing through the darkening gloom.
The blast also collapsed nearby houses, and many people were reported trapped in the debris.
A series of smaller blasts could be heard across the city later.
Prior to Saturday's attacks, a twin car bombing on January 22 near the capital's Haraj market killed 88 people, and on Thursday, 73 people were killed in a twin suicide bombing in the mainly Shiite town of Hilla, south of Baghdad.
The campaign of massive bombings in recent weeks is posing a major challenge to Iraqi and US authorities as they fine-tune a make-or-break security plan to stabilize the violent capital.
The Sadriya bomb came just hours after insurgents unleashed a series of other car bombs and shootings across the strife-torn country.
The northern oil hub of Kirkuk bore the brunt of those attacks, with seven car bombs rocking the ethnically mixed city that is claimed by both Kurds and Sunni Arabs.
In one Kirkuk attack, a suicide bomber exploded a car outside the office of the Kurdistan Democratic Party led by powerful Kurdish leader Massud Barzani, killing two people.
The attack wounded another 17 people, mainly women and children, and many more were reported wounded in the other six car bombings.
Two of the seven bombs exploded near two schools in the city but did not cause serious casualties because it was the weekend.
After the attacks police imposed a curfew on Kirkuk from 4 pm on Saturday to 6 am on Sunday.
Authorities also slapped a curfew on two other Iraqi cities, Mosul and Samarra, following outbreaks of violence there, police said.
In Samarra, gunmen attacked a police checkpoint just north of the city killing six commandos and wounding six more, local police said.
After the attack, police using loudhailers announced an indefinite curfew on Samarra, an AFP correspondent reported.
The predominantly Sunni town, 125 kilometres north of Baghdad, was the site of a February 22, 2006 attack on a revered Shiite shrine.
The attack on the Al-Askari shrine triggered sectarian bloodshed nationwide in which tens of thousands of people have been killed, mainly in Baghdad.
In Mosul, 370 kilometres (230 miles) north of Baghdad, clashes between insurgents and security forces were reported from various districts on Saturday.
Although no casualties were reported immediately, Iraq's third largest city after Baghdad and Basra in the south was also put under curfew, police Colonel Mohammed Jassim said.
Elsewhere three more people were killed in other attacks.