WASHINGTON (Reuters) - A man has been shot and wounded in a parking lot outside a restaurant in a Virginia town located 90 miles south of the U.S. capital, but authorities say they do not know whether the incident is linked to the sniper murder spree in the Washington area.

Authorities said a man was shot on Saturday night with single bullet outside a Ponderosa Steakhouse restaurant in Ashland, Virginia, and was transported to a local trauma centre for treatment. Officials said he was undergoing surgery at the Medical College of Virginia in Richmond.

Ashland is located about 16 miles north of Richmond, Virginia.

Since October 2, an elusive sniper has killed nine people in Washington and neighbouring Maryland and Virginia and wounded two others, picking off victims at random with a single bullet from a high-powered rifle. Police could not confirm if the nighttime shooting was related to the other shootings.

"We have no idea," Ashland police department official Pete West told Reuters.

The Hanover County Sheriff's Office said the area was being quarantined following the nighttime incident.

West could not identify the victim, who was alive following the incident.

"They are unaware at this time if the shooting is related to incidents in Northern Virginia and Maryland. And the area is being quarantined and treated as such," according to a statement released by the Hanover County Sheriff's Office.

HIGHWAYS BLOCKED

Authorities cordoned off major highways around Ashland in an effort to find the culprit, with a police helicopter hovering overhead.

Police have been using ballistics tests to link the October sniper shootings. The last shooting definitively linked to the sniper took place on Monday in Falls Church, Virginia, a Washington suburb. Police said the sniper fatally shot a 47-year-old FBI employee in the parking lot of a Home Depot store at 9:15 p.m. local time.

None of the previous sniper shootings took place during a weekend.

In another development, police earlier on Saturday scoured a seized truck and examined a bullet casing found inside it as they pursued a possible link to the sniper. Police said they had not ruled out that the lead might be connected to the sniper.

Police, who have said a white box truck was seen at more than one of the crime scenes, were poring over such a vehicle on Saturday and ran ballistics tests on a bullet casing found inside. They seized the truck from a rental agency on Friday near Dulles International Airport in suburban Virginia.

Police said on Saturday they would not announce the test results until Monday.

By John Poirier