A car bombing has killed 30 people and injured at least 65 in the historic booksellers' district of the Iraqi capital Baghdad.
The blast sent columns of smoke into the sky
The attack was near Mutanabbi Street, a busy area lined with book shops and open-air book stalls.
Witnesses said many shops were set on fire and more than a dozen cars were burnt out by the explosion.
Iraqi and US security forces are in the third week of a major operation to try to stem the violence in Baghdad.
The blast was the first major attack in Baghdad for several days and the most deadly since a female suicide bomber killed 40 people at a Baghdad college on 25 February.
Correspondents say the increase in checkpoints and troop numbers on the streets appear to have reduced death squad killings, but US military officials say car bombs remain a risk.
Monday's explosion sent a huge column of black smoke into the sky over Baghdad's commercial centre.
Several witnesses were quoted as saying that a suicide car bomber carried out the attack.
Mutanabbi Street - named after a renowned classical Arabic poet - is an area of mixed Shia- and Sunni-owned businesses and customers.
A witness quoted by Reuters news agency said there were women and children among the casualties. People drove the injured to hospital in private cars without waiting for ambulances.
"There was so much smoke that I was vomiting," said the witness, who was in a bookshop when its windows were blown out by the blast.
"Papers from the book market were floating through the air like leaflets dropped from a plane," said Naim Daraji, a civil servant quoted by Associated Press.
"Pieces of flesh and the remains of books were scattered everywhere," he said.
In other reported violence, gunmen killed five people when they opened fire on Shia pilgrims in two separate incidents around Baghdad.