Updated

Insurgents fired at least 10 mortar rounds at a U.S. base on the outskirts of Baghdad International Airport (search) on Wednesday, wounding 11 soldiers, two of them seriously, and starting a fire that burned for well over an hour.

That attack, along with a car bomb that exploded outside a police headquarters in Samawah, 150 miles south of the capital, Baghdad, were yet more evidence that insurgents have no plans of letting up their attacks even after the U.S. coalition authorities handed over sovereignty to an interim Iraqi government on Monday.

Despite the end of the occupation, about 160,000 foreign troops — most of them Americans — remain in Iraq to provide security and train Iraq's new security services. American officials have warned that the transfer of sovereignty would not stop assaults.

Guerrillas struck the logistics base on the edge of Baghdad's airport at about 8:15 a.m., said Lt. Col. Richard Rael, their commander. The base is operated by the New Mexico Army National Guard's 515 Corps Support Battalion.

"We're OK," Rael said. "We'll get back to business as usual."

A pall of black smoke hung over the airport for an hour after one of the 82 mm mortar rounds struck a petroleum products yard. There were no injuries from the fire.

The base has been subject to almost daily mortar attacks, but this was the first time the attacks caused significant casualties and damage.

Two people were wounded in the car bombing in Samawah, which set two other vehicles ablaze, a hospital official said.

Meanwhile, the United States was still looking for U.S. Marine Cpl. Wassef Ali Hassoun (search). On Tuesday, his status was changed from "missing" to "captured."

An insurgent group has claimed the kidnapping of Hassoun and has threatened to behead him unless Iraqi prisoners are released. Hassoun was shown blindfolded with a sword brandished over his head in a video aired on Al-Jazeera television.

Hassoun, of Lebanese descent, was last seen about a week before the videotape was broadcast Sunday, the military said.

"The circumstances surrounding the Marine's absence initially indicated that he was missing," a statement by the 1st Marine Expeditionary Force said. "However, in light of what we have observed on the terrorists' video, we have classified him as captured."

The New York Times, citing a Marine officer who spoke on the condition of anonymity, reported Wednesday that Hassoun had been traumatized after seeing one of his sergeants killed by a mortar, and was trying to make his way back to Lebanon. The officer told the paper that Hassoun sought the help of Iraqis on the base, was betrayed by them, and was handed over the extremists.

Hassoun's eldest brother, Mohammad, who lives in a Salt Lake City suburb, denied the report.

"To me it has no foundation. It's all wrong," Mohammad Hassoun said Tuesday night.

In Baghdad, a senior U.S. military official said Hassoun was missed after he failed to report for duty on June 20.

"It is highly unlikely that he was taken," the official said, on condition of anonymity. "We are investigating all possible circumstances that could have led to his failure to report to duty."

Capt. Amy Malugani, spokeswoman for the 1st Marine Expeditionary Force from Camp Pendleton, declined to comment on the report Tuesday. She also would not say what steps the Marines were taking to rescue Hassoun.

That report came after Turkey's foreign minister said Tuesday that Iraqi insurgents freed three Turkish hostages, while two other Turkish captives reportedly told their families they would soon be released.

The Turks were among dozens of people kidnapped in Iraq in recent months. Most have been freed, but several were slain — two by being beheaded.

"Our citizens have been released," Foreign Minister Abdullah Gul told state television. "We've struggled a lot for their release. We are glad to hear this news."

He spoke after the Arab television station Al-Jazeera reported that the group responsible for beheading two other foreign hostages had announced it was freeing the three Turks.

The abduction of the Turks was claimed by Jordanian terror mastermind Abu Musab al-Zarqawi, whose followers killed American Nicholas Berg last month and South Korean Kim Sun-Il last week.

Two other Turkish hostages were allowed to call their families to say they would be freed within a week after their company agreed to stop working for the U.S. military in Iraq, CNN-Turk television reported.

The fathers of the hostages told the private TV network their sons, Soner Sercali and Murat Kizil, were in good health. The two air conditioning repairmen were reported missing June 1.

Sercali's father Feridun said their employer, Kayteks, had agreed to stop doing business in Iraq.