Sandy Hook Elementary School students were sent home for the day after a bomb threat forced the evacuation of the school Friday, the sixth anniversary of the massacre that killed 20 first-graders and six educators.

Newtown police said a bomb threat was called in around 9 a.m. Friday and the school was evacuated.

The threat is not believed to be credible, Lt. Aaron Bahamonde said, but they took it seriously and will investigate fully. No one was hurt and no one was in danger, he said.

Nothing was found during a sweep of the school and police left the school ground just before noon.

There's a heightened level of anxiety in town on the anniversary and the school superintendent decided to cancel remaining classes, according to Bahamonde. Police are investigating the source of the threat.

The community is responding on social media with calls to stand with Newtown on the anniversary of the tragedy.

Sandy Hook Elementary School was evacuated this morning while a threat is being investigated by our police dept. Please stand with our community as we attempt to survive another tragic anniversary. #EndGunViolence #SandyHookStrong pic.twitter.com/qNsXADnoPr — Newtown Action (@NewtownAction) December 14, 2018

My heart is breaking. https://t.co/6OUZVpYJFx — Chris Murphy (@ChrisMurphyCT) December 14, 2018

Police said this not believed to be related to the bomb threats made nationwide Thursday. Newtown was one of the communities that did receive two threats.

The school where the shooting happened on Dec. 14, 2012, was knocked down and a new building was constructed at the same site.

Moments of silence were observed in Newtown and other places Friday morning in memory of the victims.