A suicide bomber dressed as a policeman killed a top Iraqi police chief in the volatile northern city of Mosul on Thursday as he toured the scene of a bomb blast in which 34 people died, police said.
Brigadier General Salah al-Juburi, chief of police of Nineveh Province, was killed along with two other officers as they inspected the mangled wreckage from Wednesday's bombing, which obliterated a three-story apartment block and damaged about 100 adjoining houses, officials said.
In other violence on Thursday, a leading Shiite cleric survived a bomb attack on his convoy in Iraq's shrine city of Karbala, 100km south of Baghdad, that killed two of his bodyguards, officials said.
Sheikh Abdul Mahdi al-Karbalai was slightly wounded in the blast and was treated in hospital and then discharged, security and medical officials said. Another four bodyguards were also wounded.
Karbalai is the Karbala representative of Iraq's Shiite spiritual leader Grand Ayatollah Ali Sistani and often leads Friday prayers in the Imam Hussein mosque, one of Shiite Islam's holiest shrines.
Iraqi Prime Minister Nuri al-Maliki issued an angry statement saying that those behind the Mosul attacks would be hunted down and brought to justice.
"This crime exposes the moral bankruptcy of the terrorists after a string of defeats at the hands of our armed forces," he said.
The attacks have been blamed on al-Qaeda, which US commanders say has deep roots in the ethnically diverse city 370km north of Baghdad.
"We have 34 people killed and 217 wounded in Wednesday's bombing," said Hisham al-Hamdani, head of the provincial council of Nineveh, of which Mosul is the capital.
"Whole families have vanished. There are still people trapped under the rubble. The casualty toll may increase," he said.
The US military said three Iraqi soldiers were among the dead.
Wednesday's blast, the largest heard in the restive city for several years, occurred "as Iraqi army units were conducting a raid of a weapons cache in western Mosul," said Major General Mark Hertling, commanding general of US forces in northern Iraq.
"This is a stark example of al-Qaeda's disregard for the citizens of Iraq," Hertling said.
The full extent of the damage caused by the powerful blast became evident on Thursday. Only a water-filled crater about 25m in diameter could be seen where the apartment block had stood, while surrounding houses were a mangle of buckled concrete and twisted steel pipes, a scene reminiscent of an earthquake.
An Iraqi security official said the building was being readied by the Iraqi army for use as a snipers' position to stop al-Qaeda fighters using a nearby bridge to hang victims of their kidnappings.