Insurgents killed 19 Iraqis and two U.S. soldiers Saturday in bombings across Baghdad and in northern Iraq, and kidnappers threatened to kill two Americans and a Briton within 48 hours if their demand was not met.

The deadliest attack occurred in the northern city of Kirkuk, where witnesses said a young man driving a gray Opel sedan sped down a dirt road leading to the back of an Iraqi National Guard building then blew up the vehicle near a crowd of recruits, killing 19 people and wounding 63.

Two U.S. soldiers were killed and 11 wounded in two car bombings on the road leading to the Baghdad International Airport.

In the first attack Saturday afternoon, a suicide bomber drove up beside a convoy near a checkpoint outside the airport and detonated the vehicle, wounding three soldiers, according to Master Sgt. David Larsen of the 1st Cavalry Division.

Another convoy on its way to assist the first was also hit by a car bomb, Larsen said. That attack killed two soldiers and destroyed two Humvees and a Bradley Fighting Vehicle in which some of the troops were riding.

A security alert had been issued before the attacks for travel on the airport road and U.S. Embassy personnel were temporarily prohibited from using it.

Around 10:30 p.m., U.S. forces launched an airstrike near the restive city of Fallujah on "an armed checkpoint" linked to Abu Musab Zarqawi, a Jordanian-born militant, according to a military statement. "Informants linked the checkpoint to kidnappings and executions in the Fallujah area," the statement said. "Evidence indicates Iraqi citizens have been kidnapped at such checkpoints, taken to outlying areas where they were forced to dig their own graves and then executed."

U.S. forces have bombed Fallujah almost daily for nearly two weeks. Officials have said they believe that Zarqawi, who has been linked to car bombings, kidnappings and other violence, uses the Sunni Muslim city as a base for his operations.

Kidnappers purporting to belong to Monotheism and Jihad, an organization linked to Zarqawi, threatened to kill the three hostages within 48 hours unless all Muslim women detained at the Abu Ghraib prison near Baghdad and in another prison in the southern city of Umm Qasr were released.

The hostages, two American contractors, Jack Hensley and Eugene "Jack" Armstrong, and a British engineer, Kenneth Bigley, were kidnapped Thursday at their residence in the capital. A video first broadcast on al-Jazeera television showed three blindfolded men seated before a gunman dressed in black, his face covered by a black scarf. On the video, the hostages state their names and jobs.

Armstrong's cousin, Minnta Davis, said she recognized him in the video, which was rebroadcast on U.S. television. "We only know what they're showing on television," Davis told the Associated Press. "We don't really know anything. . . . We just know there are just a lot of prayers for him."

U.S. officials have said the only women held by coalition forces in Iraq were biologists allegedly connected to a weapons program under former president Saddam Hussein. The women, Huda Salih Mahdi Ammash and Rihab Taha, are both being held at Camp Cropper near the Baghdad airport, U.S. officials have said.

The Islam Memo Web site reported it had received a message from a group holding two French journalists saying that the two hostages had been released, according to the Reuters news agency. A spokesman for the French government, which has been working to gain their freedom, told Reuters it was "premature to say whether or not this statement is authentic. We are analyzing it."

The two French journalists were kidnapped on a road south of Baghdad on Aug. 19. Two Italian aid workers kidnapped on Sept. 7 in the capital are also being held.

Meanwhile, another group said it had seized 10 hostages working for an American-Turkish company, according to a tape broadcast by al-Jazeera, the AP reported. The previously unknown group, calling itself the Salafist Brigades of Abu Bakr al-Siddiq, said it would kill the hostages in three days if the company did not leave Iraq, the network reported.

Al-Jazeera said it had received a copy of the tape but did not say how. The group said the company was an American-Turkish firm operating in Iraq but did not identify it by name.

In addition to the attacks against U.S. forces on the airport road, a roadside bomb that apparently targeted a vehicle carrying U.S. officials or contractors exploded Saturday morning in central Baghdad. The bomb missed the vehicle but hit another car carrying passengers, possibly bodyguards, witnesses said. Wissam Fawsi, 30, an iron metal worker who rushed to the scene, said one of the men was seriously injured and another was severely burned. A third ran off, Fawsi said.

For the second straight day, Iraqi security forces launched raids on Haifa Street, the scene of intense fighting last week between insurgents and U.S. forces. Witnesses said Iraqi National Guardsmen, sometimes backed by U.S. troops, made several arrests in the area Saturday.

Qasim Dawood, state minister for the interim Iraqi government, said Iraqi forces arrested 26 people whom he called "foreign terrorists" during the raids and recovered 60 rockets and large amounts of TNT and ammunition.

The bombing in Kirkuk was similar to an attack on a police headquarters in central Baghdad on Tuesday in which at least 47 people were killed and 114 were injured, many while lining up to apply for jobs. At least 69 police officers, National Guardsmen and potential recruits have been killed and another 177 wounded in the wave of violence that began Tuesday.

Dozens of potential recruits were lined up near the back entrance to the National Guard station Saturday morning. Maj. Gen. Anwar Hamad Ameen said the area was normally blocked off to traffic but had been opened to give drivers access to an adjacent gas station during a fuel crisis.

"We had plans to prevent such an attack, but the suicide bomber took the chance that the back entrance was open for the cars to get fuel, " Ameen said.

Special correspondents Khalid Saffar, Bassam Sebti and Luma Mousawi contributed to this report.

Iraqi soldiers examine the charred remains of a car bomb that exploded outside a National Guard building in Kirkuk, in northern Iraq, where a crowd of men had gathered to sign up to join. The attack killed 19 people and wounded 63.