MONROE, Connecticut  - Hundreds of US elementary school children who survived the gun massacre of 20 of their schoolmates and six staff finally returned to class Thursday at a new, heavily-guarded building.

The late start to the academic year was a turning point for survivors from Sandy Hook Elementary School in Newtown, Connecticut, which has been closed since the December 14 bloodbath.

Teachers did everything possible to transform the alternate building in the nearby town of Monroe into what Newtown schools superintendent Janet Robinson called “a very cheerful elementary school.”

Approaches to the new Sandy Hook in Monroe were decorated with handmade signs of support, as well as balloons and ribbons in the school’s green and white colors.

“Welcome we love you,” read one large bright green placard under the road sign pointing to the school. “Choose love,” another said.

And police were out in force to reassure parents that nothing like the vicious slaughter, carried out by a deranged local man armed with a military-style rifle, could reoccur.

Officers stopped every car coming near the school and an AFP reporter was ordered to leave the area after having the details of his driving license noted down.

“I think right now it has to be the safest school in America,” Monroe police Lieutenant Keith White said.

About 500 children were expected to start classes in rooms filled with the familiar furniture from their old school.

But despite the huge effort to smooth the school’s path back from horror to normality, there were plenty of nerves.

“There’s no real playbook for this,” one mother, Denise Correia, said on CNN.

“I’m not sure I’m ready yet to totally let them go,” said another, Sarah Swansiger.

Connecticut Governor Dannel Malloy dropped by Wednesday to speak to staff. Parents and students were also allowed to tour the new school ahead of the first day of classes.

The new Sandy Hook school is housed in a two-story building along a winding, wooded road next to a new middle school.

The acting principal Donna Page, who replaces the slain school head Dawn Hochsprung, said “the facility is safe, secure and fully operational.”

Page said parents would be allowed to stay in the school when it opens for classes, to provide reassurance to their children.

“We understand many parents may need to be near their children on their first day(s) of school and you will be welcome. That being said, we encourage students to take the bus to school in order to help them return to familiar routines as soon as possible,” she wrote on the school website.

In Newtown, Police Chief Michael Kehoe said patrols have increased in the weeks since the shooting, and officers have been stationed all local schools as the town struggles to get over the tragedy.

The shootings provoked a major national debate on gun control and a promise from President Barack Obama to back a bill outlawing military-style “assault weapons” such as the AR-15 rifle used in the attack.

The shooter, Adam Lanza, was laid to rest over the weekend after his father, a tax executive, retrieved his body from the authorities last week, a family spokesman said.

Lanza’s mother, whom he shot at their home just ahead of the school massacre, was buried in New Hampshire last month.