The commander of the police commandos in Baghdad, Major General Rashid Fulayah, contradicted earlier reports that the operation was officially sanctioned.
"The ministry of interior has nothing to do with this arrest and especially not the commando forces and the forces of public order brigades who are not authorized to do such operations," Maj Gen Fulayah said.
Two Syrians were among those taken away. "They took people away randomly," said one store owner on Salhiya Street, convinced it was criminal elements. "They grabbed a father and his two children but left the mother on the street shouting."
Abandoned trucks
Witnesses described how two vehicles painted with the distinctive camouflage pattern of the commandos, accompanied by another 10 unmarked pick-up trucks, blocked off the street and began taking people away.
"If they were the government, they would have investigated and asked who the people they took were," said another witness who preferred to remain anonymous.
Unattended small trucks for hauling goods lined the street after their drivers had been taken away.
The raid took about 10 minutes and the police who came to investigate claimed no knowledge of the operation.
The confusion over whether the raid was officially sanctioned or a criminal operation is a reflection of the widespread suspicion people in Baghdad have of security forces, some of whom are believed to be infiltrated by militias.
A number of other violent operations have been carried out by gunmen in uniforms, which can be easily purchased in the city's markets.
Prime Minister Nuri al-Maliki has vowed that the restoration of security to the dangerous city was one of his government's top priorities, though his efforts have been hampered by the inability of his fractious government coalition to agree on a new interior minister.
Gunmen kill students
In other violence at least 27 people died including 15 in Baghdad alone, while more than 80 people died in the previous two days around the country.
Eleven students were killed in southern Baghdad when gunmen in two cars stopped their bus and riddled it with bullets, said an official with the defence ministry.
The attack took place in the southern neighhorhood of Dura, scene of numerous attacks. The students were returning from a local technical college when they were attacked.
Two farmers from the southern city of Najaf selling watermelons along Canal Street in east Baghdad were shot dead when gunmen opened fire on them.
Also in the eastern part of the city, a civil servant with the industry ministry was shot on his way to work.
In west Baghdad, a member of the local council was shot dead by gunmen in the upscale Sunni neighborhood of Mansur.
Seven bodies were found around Baghdad, including one of a member of the Badr Brigade, a Shiite militia, while another four bodies showing signs of torture were found floating in the Tigris some 20 kilometers south of the capital.
In the violence-plagued city of Ramadi, west of the capital and the scene of daily clashes between US forces and insurgents, hospital sources reported five people killed when mortars landed on their houses.
The city of Baquba, northeast of Baghdad, was once again a focus of attacks with the killing of five civilians in different incidents, including an official responsible for water planning in a nearby village.
In the northern oil city of Kirkuk, a roadside bomb killed an off-duty policemen and the headless corpse of an Iraqi contractor was found covered with stab wounds.
In nearby Mosul, armed men on a motorcycle opened fire on a gathering of police, killing one and wounding another four.