Heavily armed militants have made a sustained attack on Iraq's notorious Abu Ghraib prison, wounding 44 US troops and 12 prisoners inside.
They struck after dark, targeting an outbuilding with a car bomb and following up with another bomb, gunfire and grenades, US officials said.
Guards fought the attackers for about an hour, calling in helicopters and tanks to restore control.
According to the US military, at least 40 militants were involved.
At least one of the attackers was killed, and it was expected that more would be confirmed dead later, US spokesman Lt Col Guy Rudisill said.
Of the US injured, only a few had serious wounds, he said.
More than 3,000 detainees are held at the jail on the outskirts of the capital, Baghdad.
It was at the centre of a scandal last year over the abuse of prisoners by US guards and before that was one of Saddam Hussein's most feared jails.
Surprise attack
Some witnesses said the second car bomb went off while US troops were trying to evacuate the casualties from the first blast.
The jail has been targeted before with mortars.
Col Rudisill said the US had had some intelligence that "something like this might happen".
"But we really don't know why this large-scale attack happened tonight," he added.
This latest attack came as both US and Iraqi officials said the level of violence has gone down since January's elections.
Nine weeks since the vote, the Iraqi parliament is due to make another attempt to appoint a speaker, the first stage in forming a government to end the political limbo here.
Correspondents say MPs were hoping to break a deadlock over the post at last-minute meetings on Friday.
