Sandy Hook Elementary School students have been sent home for the day after a bomb threat forced an evacuation on the sixth anniversary of the massacre that killed 20 first-graders and six educators.

Newtown police say the threat was made at about 9 a.m. Friday and the school was evacuated. Lt. Aaron Bahamonde says there’s a heightened level of anxiety in town on the anniversary and the school superintendent decided to cancel remaining classes.

It’s unclear whether the threat was related to the bomb threats made nationwide Thursday.

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.