U.S. forces met sporadic resistance Sunday in their move on Tikrit, birthplace of Saddam Hussein, after spiriting to safety seven missing American soldiers unexpectedly released by a leaderless band of Iraqi troops.

Marines assembled on Tikrit's outskirts and sent units in and out of the city, drawing occasional small-arms fire and rocket-propelled grenades, not the intense battle that once seemed likely there. Even so, U.S. forces did not try to occupy Tikrit right away, Pentagon officials said.

The city is the last center of Saddam loyalists known to the allies, who are already turning their attention to the task of scouring towns they skipped in the race to Baghdad.

"We have simply bypassed villages and towns and so forth," said Gen. Tommy Franks, the war commander. "And now we will go to each and every one of them, and be sure that we don't have some last, small stronghold in that country."

Three weeks after Iraqis seized them and put them on TV, the seven ex-POWs were escorted to a Marine unit on the road to Tikrit by a group of Iraqi soldiers who had given up the fight and been abandoned by their leaders.

The seven walked - some ran - into a transport plane that flew them to Kuwait for checkups, treatment for those who needed it, and briefings. The sight of their loved ones, bedraggled in their pajama-like POW garb, electrified families and communities back home.

U.S. officials, trying to determine whether the vanished Iraqi president is dead, said forensics experts had samples of Saddam's DNA and would try to find a match from bodies recovered in the bomb and missile attacks most likely to have killed him.

And on the war's other deep puzzle, the location of any Iraqi weapons of mass destruction, U.S. forces reported they held a variety of Iraqi officials, including a half brother of Saddam, who might have useful information.

Other figures from the Saddam era have certainly escaped into Syria on Iraq's western border, Defense Secretary Donald Rumsfeld said.

President Bush warned that must not continue. "They just need to cooperate," he said.

Syria's deputy ambassador to the United States, Imad Moustapha, denied his country was taking in Iraqis and said it was America's job to monitor Iraq's western border.

Franks said he expects to visit U.S.-occupied Baghdad within a week, although not in the style of a conquering commander. He said he would travel "with a very small staff for the purpose of seeing my people" in a low-key meeting.

He said Iraqis were coming forward in great numbers to tell soldiers where to find Saddam loyalists, arms caches and leads on chemical, biological and nuclear-weapons programs.

One example of cooperation stood out above all others yesterday - the delivery of the seven POWs into U.S. hands.

Capt. David Romley said Marines were met by Iraqi soldiers north of Samarra who approached the 3rd Light Armored Reconnaissance Company and had the Americans with them.

Another spokesman for the 1st Marine Expeditionary Force, Capt. Neil Murphy, said those Iraqis had been abandoned by their officers and "realizing that it was the right thing to do, they brought these guys back."

Two helicopter crewmen and five members of the 507th Maintenance Company convoy who were ambushed March 23 were let go. Two had gunshot wounds, Franks said. They were found a day after Pvt. Jessica Lynch, their POW comrade rescued in a commando raid, returned to the United States for further treatment of her many injuries.

In Pennsauken, N.J., the parents of Sgt. James Riley, 31, had just returned from church services when they heard their son had been found.

"It's just an emotional roller coaster, and we're just happy he's safe," said his mother, Jane. She spoke with her son by phone later yesterday and relayed news that the sergeant's sister, Mary, 29, had died two weeks ago from a neurological disorder after two months in a coma.

Before yesterday, 12 soldiers had been listed as POWs or missing in action.

The seven recovered yesterday were in pajama-like prison outfits or similar clothing; Army Spc. Shoshana Johnson, 30, was back in khakis as she was escorted to the plane, clutching the purple and white clothing she'd been found in, and bandaged from an ankle gunshot wound.

Young and Chief Warrant Officer David S. Williams, 30, of Orlando, Fla., were shot down in their Apache helicopter south of Baghdad on March 23.

The other recovered POWs were Spc. Joseph Hudson, 23, of Alamogordo, N.M.; Pfc. Patrick Miller, 23, of Park City, Kan.; and Spc. Edgar Hernandez, 21, of Mission, Texas, who had been shot in the elbow.

Allied forces pressed their hunt for senior figures from the vanquished Saddam era.