The threat was called into the Head O'Meadow Elementary School at about 11 a.m., according to tips from the public. NBC Connecticut reported the school was scheduled to open later than normal and no one was present when the threat was received.
Some of the students had already boarded buses - many of which were adorned with large green-and-white ribbons on the front grills to honor Sandy Hook Elementary.
"You pretty much know that it's a hoax, but it's so cruel that it's beyond description," said Geordie Elkins, 42, who has a son attending Head O'Meadow.
Elkins, who asked that his child's name not be published, said the school's principal sent an email to parents notifying them that students were getting on buses and the school was on lockdown.
The email said any students who had already boarded buses would be returned home, Elkins said. His child had not yet gotten on the bus, and though Elkins and his wife talked to their son about what happened at Sandy Hook, they decided not to let tell him why his school closed unexpectedly Tuesday.
"We just said it was canceled," Elkins said. "For him, it's like a snow day."
Few details have been released about the nature of the threat. An official with the Newtown Police Department called the lockdown precautionary and said, "There's nothing to worry about."
"This won't help things return to normal, which is what we want," said Andy Cluff, 56, who lives across the street from the school.
Officer Tim Succi of the Redding Police Department said he arrived on the scene at 11:50 a.m. Succi was blocking the school's driveway.
High school students were walking Monday down Berkshire Road toward a growing memorial at the center of Sandy Hook village.
Not far down the road, outside a white building with a permanent sign out front that read "Heaven," a row of crosses with one Star of David stood in the ground. A man in a leather jacket moved silently among them, occasionally bending down to read a name etched onto one of the markers.
"We're definitely coming together," said Marsha Daria on Monday. Daria's two children attend Newtown Middle School and previously went to Sandy Hook.
"We still are grief stricken and overwhelmed by the magnitude of the senseless tragedy, but we are strong and we'll get through."
Daria said her confidence in Newtown schools' staff and teacher made her comfortable with her kids returning to school.
Reporters Danielle Lynch, Lauren Boyer, Lyle Moran, Frank Otto, Katie Lannan and Ebony Walmsley contributed to this story.