BAGHDAD, Iraq (AP) – Suspected Shiite militiamen dressed as Interior Ministry commandos stormed a Higher Education Ministry office Tuesday and kidnapped dozens of people after clearing the area under the guise of providing security for what they claimed would be a visit by the U.S. ambassador.

Witnesses and authorities said the gunmen raced through all four stories of the building, forced men and women into separate rooms, handcuffed the men and loaded them aboard about 20 pickup trucks.

Shortly afterward, authorities arrested five senior police officers in connection with the abductions – the police chief and five top subordinates in the Karradah district, the central Baghdad region where the kidnappers struck, Interior Ministry spokesman Maj. Gen. Jalil Khalaf said.

There were varying estimates of the number of people kidnapped, but it appeared that at least 50 were seized – one of the largest mass abductions in Iraq. The assault came on a day that saw at least 117 people die in the mounting disorder and violence gripping the country.

The abductions in broad daylight raised further questions about Prime Minister Nouri al-Maliki’s commitment to wiping out the heavily armed Shiite militias of his prime political backers: the Supreme Council for the Islamic Revolution in Iraq, or SCIRI, and the Sadrist Movement of radical, anti-American Shiite cleric Muqtada al-Sadr.

Al-Maliki faces intense pressure from the United States to disband and disarm the militias and their death squads, which are deeply involved in the country’s sectarian slaughter and are believed to have thoroughly infiltrated the police and security forces.

U.S. Central Command chief Gen. John Abizaid sternly warned al-Maliki face-to-face on Monday that he must disband the militias and give the United States proof that they have been disarmed, according to senior Iraqi government officials with knowledge of what the men discussed.

So far, the prime minister has said the militias should not act illegally but has taken no tough action against them.

Al-Maliki, who leads a Shiite-dominated Iraqi government, appeared to minimize the importance of Tuesday’s kidnappings. The abductions were believed to be the work of the Mahdi Army, the heavily armed al-Sadr militia which controls the Karradah district.

“What is happening is not terrorism, but the result of disagreements and conflict between militias belonging to this side or that,” al-Maliki said in televised remarks during a meeting with President Jalal Talabani.

That response was likely to prompt deeper concerns among the U.S. military and the Bush administration. The Americans have struggled for 44 months to put in place a democratic and multi-sectarian and multiethnic government that would embrace the Sunni and Kurdish minorities, even if dominated by the Shiite majority.

Since taking office in May, al-Maliki has essentially refused to reach out to the Sunnis, who ran the country for decades under Saddam Hussein. The former Iraqi leader, toppled in the 2003 U.S. invasion, ordered the killing of hundreds of thousands of Shiites.

Iraqi officials gave wildly differing accounts of how many people were abducted in the raid on the Ministry of Higher Education office that handles academic grants and exchanges. Figures ranged from as many as 150 to as few as 45.

By late Tuesday the top estimate, given by Higher Education Minister Abed Theyab, appeared to have been inflated. Both the Interior and Defense ministries issued statements declaring that no more than 50 people were abducted and that as many as 20 victims had been released. But the lower figure included only employees known to have been at work in the building and did not count an unknown number of people in the offices on business.

Even at 50, the mass abduction would be the equal of two past kidnappings in which at least 50 victims were spirited away by gunmen.

Tuesday’s kidnapping was believed to have been in retribution for the abduction three days earlier of 50 Shiite passengers who were snatched off minibuses by Sunni gunmen at a fake checkpoint along the highway near Latifiyah, about 20 miles south of Baghdad. The gunmen killed 10 passengers before making away with their captives.

Although the kidnappers Tuesday were believed to be Shiites, it was unclear whether their hostages were mostly Sunni.

Alaa Makki, head of parliament’s education committee, said the gunmen had a list of names of those to take. Those kidnapped included the office’s deputy general directors, employees and visitors, he said.

The Iraqi Islamic Party, the largest Sunni Muslim group in the country, called the kidnapping “not only a crime but a major political farce.”

“How can 50 new vehicles move around in … the area most heavily controlled by security agencies in the middle of the day?” the party said in a statement.

The facility appeared to be an easy target. Police and witnesses said the gunmen, who they claimed numbered about 80, had closed off streets surrounding the ministry. Four guards put up no resistance and were unharmed, police spokesman Maj. Mahir Hamad said.

Makki said the gunmen claimed to be helping the government’s anti-corruption body check on security ahead of a planned visit by U.S. Ambassador Zalmay Khalilzad.

“It was a quick operation. It took about 10 to 15 minutes,” Theyab told parliament of the mass abduction. “It was a four-story building and the gunmen went to the four stories.” He said the armed men had at least 20 vehicles.

A female professor who was visiting the ministry at the time of the attacks said the gunmen, some of them masked, wore blue camouflage uniforms of the type worn by police commandos. Illegal groups, including Shiite militias who have widely infiltrated the police force, are known to wear stolen or fake police and army uniforms.

The abductions follow a series of attacks on Iraqi academics that has prompted thousands of professors and researchers to flee to neighboring countries.

Recent weeks have seen a university dean and prominent Sunni geologist murdered, bringing the death toll among educators to at least 155 since the war began. The academics apparently were singled out for their relatively high public stature, vulnerability and views on controversial issues in a climate of deepening Islamic fundamentalism.

After Tuesday’s attack, Theyab ordered university classes suspended, complaining that the government had ignored his calls for greater security. He later rescinded the order when the Interior and Defense ministries promised increased patrols.