The detentions came as officials began investigating security failings that may have allowed truck bombers into the centre of the capital.
Two truck bombs exploded minutes apart near ministry buildings on Wednesday, causing widespread destruction.
Security measures in the city have been tightened in the wake of the attacks.
Prime Minister Nouri Maliki ordered a security review after the bombings, saying they showed the need for “a re-evaluation of our plans and our security methods”.
Correspondents say the attacks raise concerns about the ability of Iraqi authorities to ensure security after taking over responsibility for protecting urban areas from US forces at the end of June.
Meanwhile, funeral processions began on Thursday as bereaved families picked up the bodies of dead relatives and carried coffins draped ed hardyin black through the streets.
The provincial council in Baghdad reportedly appealed for donations of blood, saying supplies were low because so many people had needed treatment.
At one hospital Ed Hardy shoes a doctor said staff had been operating through the night, the BBC’s Natalia Antelava reports from Baghdad.
“I have never seen anything of the sort,” said the doctor, Tara Barki, describing gory scenes as casualties had been wheeled in.
“It was a mess, Ed Hardy it was chaos, I have never seen so many casualties before,” she said.