Baghdad, Iraq ? Dozens of assailants wearing Iraqi police commando uniforms and masks kidnapped scores of people from a Higher Education Ministry office in a highly coordinated raid Tuesday morning, witnesses said.

The gunmen, armed with AK-47s and U.S.-made grenade launchers, stormed the five-story downtown Baghdad building in broad daylight and searched it room by room, randomly detaining people along the way, according to education officials and witnesses.

To assist in their getaway, the abductors cordoned off Nidal Street, only a few blocks from City Hall, with more than 30 trucks and armored sport utility vehicles. The trucks did not have license plates, witnesses said, but many did have high-caliber machine guns mounted in their back beds.

Eyewitnesses gave various estimates of the number of kidnap victims but most said at least 70 were taken. The large-scale operation, which witnesses said took only a matter of minutes, was among the biggest and most audacious kidnapping episodes yet in a city where abductions for financial or sectarian reasons have become routine.

In some cases, victims eventually have been released after ransom was paid or have yet to be found. But in many incidents, tortured and handcuffed bodies are all that have later turned up on Baghdad’s streets.

Iraqi security officials inspect the reception area at the scientific research institute in Baghdad, Iraq. Gunmen in Iraqi police commando uniforms kidnapped more than 70 staff members Tuesday morning from the government research institute in downtown Baghdad in the largest mass abduction since the start of the U.S. occupation.

Kidnappings by men in police uniforms have become among the most feared because relatively few victims have returned alive.

Interior Ministry spokesman Abdul Kareem Khalaf said five senior police officials were detained and interrogated following the morning kidnappings, including the police chief in charge of the Karada neighborhood in southeast Baghdad where the incident took place. Khalaf declined to say whether it was believed the officials were directly involved, but said that they were, at the very least, negligent for allowing the abductions to occur under their watch.

“They could have reported to us that this raid took place,” Khalaf said. “These people who raided that building are not policemen at all, they are just criminals.”

Khalaf said 20 of the captives, among them Sunni Arabs, Shiites and Christians, were hastily freed because of checkpoints set up by the Interior Ministry. “We closed more than 20 neighborhoods in East Baghdad and cut them off. They had to throw some of the people out of their cars so they wouldn’t get caught,” Khalaf said.

His account of captives being freed could not be independently verified.

Those taken included 17 security guards stationed at the facility, the Scholarship and Cultural Relations Directorate of the Higher Education and Scientific Research Ministry. Also abducted were ministry employees and visitors who had business in the building. The raiders separated men from women, locking the men together in a daisy-chain with plastic flexicuffs and loading them into vehicles at gunpoint.