The federal government issued an ultimatum yesterday to people who own land designated for the Flight 93 memorial in Western Pennsylvania: They have one week to reach an agreement on the sale of their land or the government will initiate proceedings to seize it.

The order came hours after Interior Secretary Ken Salazar and U.S. Sen. Arlen Specter (D., Pa.) met with people who own 500 acres in and around the Shanksville area, where Flight 93 crashed on Sept. 11, 2001, and with victims' relatives eager to see the memorial built in time for the 10th anniversary of the terrorist attacks.

"After meeting with the landowners and the Park Service today, I have high hopes that the parties are close to agreement and will be able to reach consensus over the land in the next week so we can keep the memorial on track without using eminent domain," Salazar said. "Only if the parties are not able to reach agreement will we have to use the last resort of eminent domain to acquire land."

Kendra Barkoff, Salazar's spokeswoman, said the deadline was essential to keep the construction on track. He directed National Park Service officials to meet with landowners early next week and report to him by Friday.

The decision by the National Park Service last month to pursue eminent domain touched off fierce criticism in an area where local residents have been deeply involved in efforts to plan the park and establish and staff the temporary memorial at the crash site. Two local members of the Flight 93 Federal Advisory Commission were so angry about the government's seizure plans that they resigned.

Tim Lambert, who owns 163 acres immediately adjacent to the crash site, said he was heartened that Salazar met with the landowners.

"Never at any point before did the National Park Service sit down with landowners," said Lambert, who wants to donate six acres to the park. "I am optimistic that if both sides sit down we could reach agreement within days."

But others, like Pat Svonavec, whose family owns 275 acres at the site, does not believe the timetable allows for thorough negotiations.

"I'm going to give them, certainly, the benefit of the doubt," Svonavec said. "I want to be a realist. I don't think there's enough time."

Victims' relatives say a quick resolution is needed in order to complete the $58 million memorial in time for groundbreaking on Sept. 11.

"We're pushing it now," said Patrick White, vice president of the Families of Flight 93, whose cousin Louis Nacke of Bucks County was aboard the plane. "What we heard today was that they are committed to the time line; that was their overarching message."

Last week, the Park Service acquired about 950 acres for the park from a coal company, the single largest acquisition.

One way or another, landowners will receive fair market value for their properties, Salazar said. Complicating the appraisal process is the abundance of natural resources above and below the land: timber, coal, and natural gas.

The park would be dedicated to the memory and heroism of the 40 passengers and crew who lost their lives when the hijacked plane crashed in Shanksville, 65 miles southeast of Pittsburgh. Specter and Salazar said yesterday the park design should also recognize the contributions of the landowners.