Two buses speed south from Baghdad towards Najaf Sunday bearing the bodies of people killed in an attack, as other buses return carrying upside-down coffins, the dead they held now buried.

The bodies are bound for Wadi al-Salam, the world's largest cemetery, at the shrine of Imam Ali, one of the holiest sites in Shiite Islam.

The journey began in Sadr City, a Shiite area of north Baghdad, where bombs targeting mourners killed at least 73 people and wounded more than 200 on Saturday.

At the site of the blasts, Jabbar Abdulsahib stood under the metal frame of a funeral tent targeted in the attack, receiving condolences over the deaths of two grandsons -- Mussa, aged three, and Hussein, 10.

His son was wounded in the attack, so Abdulsahib rushed him to a hospital, he said.

"Qadissiyah Hospital looked like a slaughterhouse. Pools of blood inside and outside, wounded people in the hallways, on the floor, helpless," he said.

"Even those who died did not get rest as there were not enough places to keep the bodies," he added.

Some, including the bodies of his grandchildren, had to be taken to Najaf for burial that night.

Abdulsahib stopped speaking and stared upwards, trying not to cry, but the tears came anyway.

"People were looking for their sons here, carrying body parts without knowing if they belonged to them," he said.

A nearby group of women began screaming, beating their chests and heads as a bus brought in a coffin wrapped in a green sheet.

Three buses with coffins drove by, and then another stopped.

Four men carried a coffin holding the body of Ali Adnan to the vehicle, and secured it to the roof.

Driving to Wadi al-Salam

A group of men and women, including Adnan's pregnant wife, boarded the bus, and it left with another one for the drive south.

As the two buses headed towards Najaf, relatives of the dead stared out of the windows, as other buses bearing now empty coffins travelling in the opposite direction.

Adnan's relatives stopped and washed his remains at a one-storey building near Wadi al-Salam Cemetery.

One of Adnan's uncles, who did not give his name, said they would not take his body to the actual shrine of Imam Ali, as is the tradition, because it had been too badly mutilated.

Instead, they returned the corpse in the coffin to the roof of the bus and drove into Wadi al-Salam, which by legend is large enough to hold all of the world's Muslims.

"This is not the first time we've buried someone we love, and not the second, nor even the fifth," Naim Saadallah, another uncle, said after helping carry the body to the grave.

"We are used to burying people. We will bury him today, and we will go back to our lives."

Adnan's relatives gathered around the grave, and an old man sat nearby reading from the Koran, the Muslim holy book.

As they began to lower the body into the grave, the women began shouting. His mother cried out: "Oh father, oh mother, he broke my heart. Allawi, you break my heart."

Adnan's wife tried to reach out to his body but the men held her back. She sat down, sobbing and beating her head with one hand.

The ceremony was over quickly, and the mourners went back to the bus. Adnan's sister sat at the very back, looking out of the window towards his grave, weeping.

Her brother's empty coffin was placed back on the roof of the bus, upside down.

As he walked to the bus, one of Adnan's uncles thought about those responsible for the attack.

"The man who killed Ali, how will he face his God today? What is he going to tell him, I wonder?"