BAGHDAD, Iraq - Insurgents fired at least 10 mortar rounds at a U.S. base on the outskirts of Baghdad International Airport today, 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. 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 to 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.