Marine biologists are trying to determine whether a shark spotted at Cape Cod National Seashore was a great white. The shark in question was seen attacking a seal between High Head, in Truro, and Race Point Beach at Provincetown this past weekend.

"If verified, this will be the first great white shark sighting north of the Chatham/Orleans beaches, close to the protected beaches of the seashore," Cape Cod Superintendent George Price said in a statement posted on the seashore's website Monday. "Seashore rangers have interviewed the witness and are reviewing a series of photographs. Dr. Greg Skomal, Massachusetts Marine Fisheries and regional great white shark expert, was already on the water off Chatham spotting for sharks and was en route to investigate the incident.

"The approximate location of this reported sighting is 2-3 miles from two life-guarded beaches -- Race Point Beach and Head of the Meadow Beach -- and along the off-road vehicle corridor," the superintendent said.

The area off of High Head is the location of a sand bar that attracts hundreds of gray seals at low tide, said Superintendent Price. Although seals are a primary food source for great whites, the Chatham area to the south has been the primary feeding grounds where gray seals can be found in the thousands, he said.

Last month portions of national seashore beaches were closed due to great white sharks swimming just 100 yards off the beaches.

The Chatham/Orleans beaches are within the boundary of the National Seashore, but are owned and managed by the towns. Seashore staff is on extra alert and beaches will be closed to swimming if sharks are sighted near a protected beach, said the superintendent.