Unidentified attackers on Wednesday hit the al-Rawafid Security Co. at 4:30 pm (local time) and forced the workers into seven vehicles, including several white SUV's, said Interior Ministry official Maj. Falah al-Mohammedawi.
The company, one of dozens providing protection for businesses and other clients in the violence-plagued country, is located in Zayouna, a volatile mixed Sunni-Shia neighbourhood in east Baghdad.
Its employees include many former members of Saddam Hussein's security forces.
Earlier, a roadside bomb aimed at an Interior Ministry security force killed two people and injured five others in one of several explosions in the capital.
Police Major Abbas Mohammed Salman said Wednesday's bomb was hidden under a parked car near the University of Technology.
The interior minister was not in
the convoy during the attack
It exploded as police from the interior minister's protection force were driving through central Baghdad in two vehicles. The minister was not in the convoy.
The dead were policemen. One officer was among the injured, he said.
Several other explosions on Wednesday caused no casualties, the police said.
Meanwhile, a US military patrol found 18 bodies - all males - in an abandoned minibus on Tuesday night on a road between two notorious mostly Sunni west Baghdad neighbourhoods.
The bodies were brought to Yarmouk Hospital and lined up on stretchers for identification. Most had bruising indicating they were strangled and two were shot, said Dr Muhanad Jawad, who initially thought they had been hanged.
Police believed at least two of the men were foreign Arabs.
Police found the bodies of six more men - four of them strangled and two shot - discarded in other parts of the city.
The bodies in civilian clothes appeared to be that of young and middle-aged men.
Two were wounded in a roadside
Police and hospital officials, aware of the potential for sectarian anger if the victims were identified as either Sunni or Shia Muslims, said they had no clues to the victims' identities.
Similar incidents in the past have provoked anger among Iraqis.
The bodies were found near the Amriya district of western Baghdad.
The area has been a stronghold of Sunni fighters. Local people have also accused the Shia-led, US-backed government's police and other security forces of abducting and killing Sunni civilians - an accusation the police deny.
The dumping of bodies bearing signs of torture and killed execution-style has become a feature of violence in Iraq.
Official figures and anecdotal evidence suggest an increase in such killings since the destruction of a major Shia shrine in Samarra two weeks ago on 22 February, which sparked reprisal attacks.