Friday prayers had just ended and hundreds of worshippers were leaving when explosions rocked the Buratha mosque in the Iraqi capital, Baghdad.
The mosque is popular and usually packed for Friday prayers
Victims were carried away in blankets, carts and trucks as families searched frantically for their relatives.
"I saw a woman dressed in a traditional abaya (head-to-toe veil) blow herself up at the main entrance of the mosque as innocent worshippers were stepping out," said Mustafa Ahmed, a photographer for the AFP news agency.
Mr Ahmed, who suffered a shrapnel wound in his right leg, described a "sea of blood" as a second suicide bomber blew himself up when worshippers rushed to the site of the first blast to help the injured.
Layla al-Khajifa, one of the BBC's Iraq day panellists, said she called a friend whose brother is the imam, when the blasts happened.
People were "packed in to the door of the mosque...It's very sad and very bad," Ms Khajifa said.
"The Friday prayer at that mosque is one of the biggest ones in Baghdad," she added.
Ms Khajifa herself had visited the mosque, in the north of the capital, the day before.
Faced with a high number of injured, the Baghdad city council appealed on local television channels for people to donate blood.
"My house is opposite to the mosque and when we heard the first huge blast I ran to make sure my father, who was praying there, is safe," a Baghdad resident, Naba Mohsin, told Reuters.
"When I entered the mosque a second huge blast occurred and I saw a big blast with flames. I was thrown, then I woke up in the ambulance. I want to know if my father is alive."
A witness told the BBC of the dozens injured in the blasts. "The number of the wounded was huge, we didn't even have a chance to see to them," she said.
At the scene of the attacks, local fireman Jawwad Kathim called the blasts a "cowardly act".
"Every time I see these bloody scenes it tears apart my heart," Reuters quoted him as saying.
Another of the BBC's panellists, Essam Hamoudi, used to go regularly to the mosque when he lived in Baghdad. He spoke of his utter shock at hearing about the blasts, believed to be a triple suicide attack.
"It is such a holy place and it has a big area. You could hear the leaves shake in the trees when so many hundreds of Shia Muslims bowed down to pray," he said.
"It is over 1,000 years old and I used to go there because there is a holy well with holy water on the site - where Imam Ali visited centuries ago."