A U.S. Army brigade that seized Baghdad's international airport in heavy fighting two weeks ago moved into the eastern half of the capital today, taking over security duties from U.S. Marines.

Separately, the Associated Press reported that Saddam Hussein's son-in-law and one of the former president's bodyguards surrendered to an Iraqi opposition group after returning from hiding in Syria, the group said today.

The son-in-law, Jamal Mustafa Abdallah Sultan Tikriti, and the bodyguard turned themselves in to the Iraqi National Congress in Baghdad, a group spokesman in London said. The men could have information on the whereabouts of Hussein, the spokesman said.

Tikriti is married to Hussein's youngest daughter, Hala, and was deputy head of the Tribal Affairs Office. He ranks No. 40 of the 55 top Iraqi officials sought by the United States and its allies.

He was being questioned by intelligence officers of the Free Iraqi Forces, the Iraqi National Congress's armed wing, and would be turned over to the U.S. military in Baghdad "in a matter of hours, not days," said Haider Ahmed, a spokesman for the London-based umbrella group of opponents to the former Iraqi president.

On taking over security in Baghdad, the 3rd Infantry Division's 1st Brigade quickly began making its presence felt, positioning tanks and other armored vehicles around banks, hospitals and other key installations to prevent looting. Patrols of M2 Bradley Fighting Vehicles and Humvees mounted with machine guns rolled through streets increasingly jammed with traffic as tensions eased and Baghdad showed signs of a gradual return to normal.

"We have not had any reports of looting today," said Col. William F. Grimsley, the 1st Brigade commander, an Arlington-born former resident of Northern Virginia who graduated from McLean High School. He said an 11 p.m. to 6 a.m. curfew imposed two nights ago appears to be helping to reduce the looting, which was rampant across Baghdad in the days after U.S. forces seized the capital.

In an interview at his new headquarters at an Interior Ministry complex, Grimsley said curfew violators were being detained overnight, then released in the morning with a warning.

The Marines who had been in eastern Baghdad pulled out to regroup in the southern half of the country under a U.S. military redeployment plan. Army units will now control all of this sprawling capital of 5 million people, as well as the northern half of Iraq.

The redeployment sharply reduces the number of troops in Baghdad. Commanders did not release figures on the size of the reduction.

The Army today provided security for the arrival of the first convoy of U.N. food aid to reach Baghdad since the U.S. invasion that resulted in the fall of Hussein on April 9. U.N. officials said the arrival of the 50-truck convoy from Jordan signified the opening of an aid corridor that should keep Baghdad well supplied with food.

Grimsley said the aid convoy, consisting of 1,400 tons of wheat flour, rice, feed grains and baby formula, would be stored under U.S. protection in a warehouse that was found empty after apparently being looted. Under Hussein's government, food was stored in state facilities and rationed, ostensibly because of U.N. economic sanctions that were imposed following Iraq's 1990 invasion of Kuwait.

The U.N. shipment, supplied by the World Food Program, is to be distributed early next month.

"We expect food supplies might start to run out by the end of this month and we plan to have enough food stocks ready for distribution by the beginning of May," program spokesman Maarten Roest told the Reuters news agency in Jordan.

Word that the shipment had arrived was greeted with relief by Baghdad bakers, who have been growing worried about shortages that have tripled the price of flour since the war began.

Besides protecting the U.N. food, 3rd Infantry Division troops were busy safeguarding museums, government buildings and other key sites, including banks stocked with large quantities of gold bullion.

"We're trying to saturate the streets with Americans, not huddle in our enclaves," Grimsley said. With self-protection the top priority of U.S. soldiers here, "sometimes the natural inclination is to huddle behind walls," he said. But it is important to show that the troops are providing security, he said.

Although heavy gunfire of uncertain origin was heard late Saturday and tracer bullets lit up the night sky -- "Beirut rain," Grimsley called it -- the reception for his brigade has been largely positive, he said.

"The people here are generally very friendly, or at least neutral," Grimsley said. "And I'm more than willing to accept neutral."

He said his soldiers would put some effort into clearing the streets of burned-out cars, buses and trucks, dead animals, and other debris that disrupts the flow of traffic and poses health hazards.

U.S. Marines leave Baghdad as smoke rises from an agriculture storage facility torched by looters. The Army's 3rd Infantry Division took over security duties, guarding the first U.N. food shipment and key sites.