FALLS CHURCH, Va. (AP) - A woman was shot dead outside a Home Depot store Monday night, and police were trying to determine whether the slaying was related to the sniper spree blamed for eight killings in the region in the past 12 days.

Police swiftly closed highways in the area, about 10 miles west of the nation's capital, and said they were on the lookout for a white van from which the shooter might have fired. Witnesses at some of the earlier shootings also reported seeing a white van or truck.

The woman was felled by a single shot at about 9:15 p.m., authorities said. All the other deaths in the spree were also caused by one shot, and two people also were wounded by a single bullet.

Members of a Maryland task force investigating the sniper attacks were conferring with Fairfax County authorities to see if Monday's victim was the sniper's ninth.

"It's too early to tell (if the shooting is linked), but we are working it and investigating it with that potential in mind," Fairfax County Police Chief Tom Manger said at a news briefing.

He said there were several witnesses.

Virginia State Police said they were on the lookout for a cream-colored Chevrolet Astro van with the right rear taillight out, last seen traveling east on Route 50 from Falls Church. Interstates 66 and I-95 are nearby.

The Home Depot is located in the Seven Corners Shopping Center, a 450,000-square-foot strip shopping center with a parking garage. The victim's body lay under a sheet 30 yards from the store entrance, in the parking lot in front of the store

The woman was shot in the head as she and her husband loaded packages into their car's trunk, said Ellen Qualls, a spokeswoman for Virginia Gov. Mark R. Warner. Someone fired the fatal shot from a van, she said.

"There's some pretty decent eyewitness information that maybe we haven't had in some of the previous shootings," Qualls said.

Kristin Reed, a supervisor at the Barnes & Noble bookstore in the sprawling strip mall, said six employees were locked inside the store with an FBI agent.

"Cops and cops and more cops," Reed said of the scene outside. Shopper Raymond Massas said he "heard one shot. Not very loud, like a snap. After that I heard people start panicking."