That is fewer dead than was thought originally, when the toll was put at eight people, including two lawmakers However, there are unconfirmed reports by Iraqi media that in addition to Sunni legislator Muhammad Awad al-Juburi, who was killed, two other members of parliament have died of their injuries.
Iraqis, and the rest of the world, have come to regard the sound of explosions as almost normal in many parts of the city -- in markets, in business districts, and in residential areas.
But it is so rare that suicide bombers get into the heavily protected Green Zone of federal buildings in the city center that this attack seemed to break all the rules.
Iraqi parliamentarians meeting today to discuss the attack acknowledged that fact. But they also said the attack now shows that all Iraqis -- normal citizens and officials -- are on the front line together against insurgents.
"The [blast] came to confirm the bond between [parliament] deputies and those who elected them, and that we are in the same boat," parliament speaker Mahmud al-Mashhadani said.
"What happens daily to our people is greater than what happened to us [in parliament], and that will not loosen the determination of the deputies," he added. "Instead, it will increase their resolve to challenge terrorism and obstacles."
Differences Over Security
How could a suicide bomber carry out an operation in the Green Zone? The investigation, already launched, could take days or even weeks more to arrive at answers. But already, some of the main areas where investigators will look are becoming clearer.
Iraq's national security adviser, Muwaffaq al-Rubay'i, noted after the bombing that the parliament building has its own security arrangements.
And he suggested there was friction in the parliament's relations with larger security structures over the procedures that should be in place at the building.
Rubay'i, who is an adviser to Prime Minister Nuri al-Maliki, told reporters, "We advised the parliament that no visitors should go into the building and, secondly, that they should give us responsibility for the force protection and we would be in charge, but they didn't want it."
The security disagreements between the parliament and the government may stem in part from the fact that members of parliament insist on their right to have their own security guards.
Radio Free Iraq reported that deputies surround themselves with bodyguards drawn from among their closest relatives or loyalists.
Some legislators say that leads to friction, as bodyguards on occasion demand exemptions from searches at checkpoints.
Wail Abd al-Latif, a deputy from the secular Iraqiyah bloc, told the U.S. daily "The New York Times" that "some of the lawmakers' guards make trouble at the checkpoints, some of them refuse to be searched. They are not very professional."
Green Zone Still Safe?
It is still too early to know whether frictions of this kind at checkpoints might have contributed to the success of the April 12 attack.
Theories in the media on how the attack took place range from security lapses, to inside cooperation from some security guards with the bomber, to smuggling of bomb-making materials into the Green Zone over time.
The attack is the most serious to occur in the Green Zone since October 2004. At that time, two bombs killed six people.
But there have been repeated signs in recent weeks that security inside the Green Zone may not be as tight or effective as the infrequency of deadly attacks suggests.
Security officials say that two weeks ago, two unexploded suicide vests were found inside the zone. And in November, a bomb exploded inside the armored car belonging to the speaker of parliament.
Radio Free Iraq has reported that the Green Zone is protected by five echelons of security. They include U.S. troops, Iraqi troops, guards contracted by the U.S. military, and members of Georgian forces that participate in the international coalition.
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