GORHAM – Gorham authorities are on heightened alert following a message posted on a social website that high schools in Cumberland and York counties would be targeted with harm on Friday, Dec. 21.

Gorham School Superintendent Ted Sharp said in a letter to parents Wednesday that law enforcement has been unable to confirm the authenticity of the threat.

Sharp wrote in a letter posted on the school department website that there would be an increased presence of police at Gorham High School on both Thursday and Friday this week. Patrols at the town’s three elementary and middle schools also will be stepped up.

“While this threat has only been directed at high schools in southern Maine, we will, as stated, intensify our vigilance at each school,” Sharp wrote.

The threat was posted on Facebook, but, Sharp said, the origin has not been determined.

A law enforcement/safety official will also be assigned at each school, Sharp said.

Sharp urged in his letter that parents “be ever vigilant” to conversations, email exchanges, and postings on social websites and report any major changes in behavior in their children.

Lt. Chris Sanborn of Gorham police said Wednesday evening there has been some basic information with a non-specific threat to high schools in Cumberland and York counties of a school shooting on Friday. Sanborn said there’s no confirmation of a specific threat to Gorham.

Sanborn said the Gorham Police Department has added additional personnel and stepped up patrols Wednesday evening. He said Gorham detectives are following leads in an open investigation also involving other agencies.

Gorham Police Department can be reached at 222-1660; Gorham High School Principal Chris Record at 222-1128; and Sharp, 222-1012.