The U.S. commander in charge of training Iraqi security forces says the deadly Baghdad bombings obviously represent a lapse in security and that he's personally frustrated with the pace of some training there.
Army Lt. Gen. Frank Helmick said at a Pentagon news conference Thursday that he isn't certain he can complete some of the high-tech training - including for Iraq's air force - by the time U.S. troops are scheduled to leave at the end of 2011.
He said he didn't know who was responsible for Wednesday's bombings, which killed about 100 and wounded 500.
Iraqi Prime Minister Nouri al-Maliki is blaming Sunni insurgents.
Iraq arrested 11 senior security officers Thursday as public anger mounted, and the government admitted negligence at checkpoints permitted Wednesday's slaughter.
The police, army and intelligence chiefs detained are being questioned about security failings that culminated in the attacks, just minutes apart outside the ministries of finance and foreign affairs.
Maj. Gen. Qassim Atta, spokesman for the Iraqi army's Baghdad operations, said regulations prohibit large trucks such as those that exploded from coming close to central Baghdad, where the two ministries are located.
"An investigation has been launched into how these trucks got into the area," he said.
The admission came after Wednesday's attacks, the country's worst day of violence in 18 months, prompted outrage among Iraqis at how the bombers had been able to commit such atrocities.
"How can they allow a truck to pass through this important street, near this important ministry?" asked a distraught foreign ministry worker, carrying his clothes in a bag as he started to search for a new home because the doors and windows of his apartment had been destroyed.
"This can't be done even in Afghanistan or Africa," the man, in his 40s, told Agence France-Presse.
Despite Thursday's heightened state of alert, two people were killed and 10 wounded by a bicycle bomb in a market in the largely commercial al-Rasheed street in central Baghdad, security and medical officials said.
Elsewhere, two Kurdish men were killed and two others wounded when gunmen attacked a political party's offices overnight in the disputed northern Iraqi province of Diyala, security and medical officials said.
Six people were killed and 66 were wounded by three attacks - a bomb exploding on a bus, a roadside bomb and a mortar attack - in Hilla, 65 miles south of Baghdad.
Maliki aide Ali Musawi said Wednesday's truck bombs would not derail the government's quest to restore long-term stability to Iraq.
"They are trying to undermine all of Maliki's successes and reduce his popularity," Mr. Musawi said, but "the gains which we achieved are greater than anything they are trying to do."
Some analysts, however, said the attacks had shattered attempts by Mr. al-Maliki to portray himself as a guardian of security ahead of nationwide parliamentary elections in January.
"Maliki is clearly the man who wanted to be the symbol of increasing security and security capabilities, and that is clearly not the case," said International Crisis Group analyst Loulouwa al-Rachid.