Not the Sandy Hook Elementary in Connecticut, but a different school with the same name in Virginia. From WRC-TV:
A man was arrested at Sandy Hook Elementary School in Strasburg, Va., Wednesday, according to the Shenandoah County Sheriff’s Office.
Christopher Garret Johnson, 33, walked into the school with a 4-foot long two-by-four labeled “High Powered Rifle” about 11:40 a.m., the sheriff’s office said.
He was met by school staff, then detained by a sheriff’s school resource officer. He was arrested and taken into custody without incident.
Police speculate that he was trying to make some sort of point about gun control and the 2nd Amendment. He’s being held with without bond pending a mental health evaluation. Fortunately he did not make contact with any students.