A car bomb outside the Iraqi education ministry in Baghdad has killed at least six people, Iraqi officials say.
Anguished relatives heard bad news at Noman hospital
The blast in the mainly Sunni Adhamiya district damaged the ministry building and destroyed 31 cars.
There was no claim of responsibility for the attack, the latest of many in Iraq since US-led forces invaded to depose President Saddam Hussein.
Elsewhere US artillery and jets have been bombing suspected insurgents in Falluja and Ramadi west of Baghdad.
Guards at the education ministry said the bomber tried unsuccessfully to ram the gates outside the heavily-protected compound before detonating his charge.
Medics at Noman hospital said six people were killed, while officials at a second hospital reported two more deaths.
Two Iraqi women are thought to be among the dead.
The Adhamiya blast damaged water pipes and 31 cars
Civilians have meanwhile continued to flee the embattled insurgency stronghold of Falluja, west of Baghdad.
Iraqi Prime Minister Iyad Allawi has warned the city faces a military assault if it fails to give up foreign fighters the US military and Iraqi government say are sheltering there.
However, interim Iraq President Ghazi Yawer has said he opposes any military solution to the stand-off between US forces and insurgents in the Sunni-dominated city.
In Baghdad, two Iraqi guards abducted along with several foreigners on Monday have been released, Iraqi police said.
A US citizen, a Nepali and two other Iraqi guards are still being held hostage after gunmen stormed their house in the upmarket Mansour district.
Monday saw the assassination of Baghdad's deputy governor in an armed ambush on his car.
Two Iraqi national guardsmen were injured in a roadside bomb attack against a convoy near Abu Ghraib, west of Baghdad, an Interior Ministry spokesman said.
The US defence department has said that 6,500 US troops have had their tours of duty in Iraq extended by two months.
The move is being made in order to boost troop numbers and capabilities ahead of Iraqi elections in January.
Some 6,500 troops who were due to have returned before the Iraqi election scheduled for January are to have their tours of duty extended by between 30 and 60 days.
The US wants the most experienced units to stay on in Iraq
Keeping troops in a combat zone longer than originally planned is never popular with the soldiers themselves, says the BBC's Pentagon correspondent, Nick Childs.
But Pentagon officials say these units were chosen in part because they were originally slated for tours of only 10 months, so extending them will not break the 12-month limit the Pentagon has been aiming at for the maximum length of missions in Iraq.
The key motivation, according to Pentagon officials, is to keep experienced units in the country during what will be a critical period.
These are 3,500 troops from the 2nd Brigade of the 1st Cavalry Division and 3,000 personnel from the headquarters unit from the 1st Infantry Division.
One of their replacement units - the headquarters unit for the 42nd Infantry Division - is being delayed, so the net effect will be to increase troop numbers by a relatively modest 3,500.
According to the latest official Pentagon figures, there are currently about 134,000 US troops in Iraq, as well as about 25,000 other coalition forces.
With the normal troop rotations that are going on, which allow for some overlap of forces, Pentagon officials are suggesting that there may be up to 142,000 US troops in Iraq by January.
This is all a far cry from the Pentagon planners' hopes at the beginning of the year, our correspondent says.
Now Pentagon officials - from Defence Secretary Donald Rumsfeld down - concede that the insurgency has become both more widespread and sophisticated than they had anticipated.