Two suicide bombers, one in an explosives-laden car and the other on foot, hit a cluster of funeral tents packed with mourning families in a Shiite neighbourhood in Baghdad, the deadliest in a string of attacks around Iraq that killed at least 92 people on Saturday.
The assaults, the latest in a months-long surge of violence, are a chilling reminder of insurgents' determination to re-ignite sectarian conflict more than a decade after the US-led invasion.
Thousands of Iraqis have been killed in violent attacks in recent months — a level of bloodshed not seen since Iraq pulled back from the brink of civil war in 2008 — despite appeals for restraint from Shiite and Sunni political leaders.
The attack on the funeral was one of the largest single terrorist assaults on civilians in Iraq in recent years. It happened shortly before sunset in the densely populated Shiite neighborhood of Sadr City in northeastern Baghdad.
Police said at least 72 people were killed and more than 120 were wounded in that attack. One bomber was able to drive up near the tent before detonating his deadly payload, and another on foot blew himself up nearby, police said.
The explosions set the tents and several nearby cars on fire, sending a towering plume of thick black smoke over the city.
"I saw several charred bodies on the ground and tents on fire and also burning cars. Wounded people were screaming in pain," said Sheik Sattar Al-Fartousi, one of the mourners.
"The scene was horrible. The funeral turned into an inferno."
He said the first blast went off as dinner was being served in one of several tents set up for the funeral of a member of the Al-Fartousi tribe. He estimated that more than 500 people were attending the event.
Civilian pickup trucks loaded with casualties and ambulances with sirens blaring were seen racing from the scene.
Hussein Abdul-Khaliq, a government employee who lives near the bomb site, said the tents were packed with mourners when the blasts went off.
He described seeing several lifeless bodies on the ground, and wounded women and children. The clothes of several victims were soaked with blood, and firefighters had to leave the scene to refill tanker trucks with water as they struggled to contain an immense blaze, he said.
"This funeral was not a military post or a ministry building, yet it was still targeted," Abdul-Khaliq said. "This shows that no place and no one is safe in Iraq."
Less than two hours after the funeral attack, another car bomb blast struck a commercial street in the nearby Ur neighborhood, killing nine people and wounding 14, according to police.
Earlier in the day, insurgents launched a suicide attack on a police commando headquarters in the city of Beiji, an oil refining center 250 kilometers (115 miles) north of Baghdad.
Guards managed to kill one suicide bomber, but the three others were able to set off their explosive belts inside the compound, killing seven policemen and wounding 21 others, police said.
In other violence, gunmen shot and killed two prison guards after storming their houses in a village near the restive city of Mosul early Saturday. Two soldiers were killed and four others were wounded when a roadside bomb struck their convoy in Mosul, which is 360 kilometers (225 miles) northwest of the Iraqi capital.
Medics in nearby hospitals confirmed the casualty figures. All officials spoke on condition of anonymity because they were not authorized to speak to media.
There was no immediate claim of responsibility for the day's attacks. Al-Qaida's local franchise in Iraq frequently targets Shiite civilians and security forces in an attempt to undermine public confidence in the Shiite-led government in Baghdad.
Saturday's violence came as voters in the northern Kurdish autonomous region cast ballots in local elections for the Kurdistan Regional Government's 111-seat legislature. Iraqi Kurds are looking to bolster their autonomy while insulating their increasingly prosperous enclave from the growing violence roiling the rest of the country.
The pace of violent attacks in parts of Iraq outside the three-province Kurdish region has spiked sharply since security forces carried out a deadly crackdown on a Sunni protest camp in northern Iraq in April. Iraq's minority Sunni Arabs have been protesting against the Shiite-led government since late last year, alleging discrimination and criticizing the application of tough anti-terrorism measures against their sect.
Sunni extremists have been trying to capitalize on those Sunni-Shiite tensions, which are being inflamed by the sectarian divisions reflected in the civil war in neighboring Syria.
The Iraqi branch of Al-Qaida is fighting among the largely Sunni rebels in Syria even as it steps up attacks inside Iraq. It earlier this year changed its name to the Islamic State of Iraq and the Levant — a name evoking its aim of creating a new Islamic caliphate that ignores regional borders drawn by Western powers.
Mainstream Iraqi political and religious leaders have appealed for calm. Earlier this week, Shiite, Arab Sunni and Kurdish political leaders signed what they called an "honor pact" against the rising violence. The pact calls for safeguarding national unity, political dialogue over political problems, firm action against terrorist activities and a fair distribution of government posts among all Iraqi sects and ethnic groups.
More than 4,000 people have been killed in violent attacks between April and August, United Nations figures show. Another 489 have died so far in September, according to an Associated Press tally.