Sandy Hook School evacuated after receiving bomb threat on shooting anniversary

Sandy Hook Elementary School has been evacuated after a bomb threat was made on the sixth anniversary of the mass shooting that killed 20 primary school children and six teachers.

It came a day after Columbine High School, where 13 people died in a shooting in 1999, was placed on lockdown amid bomb and gun threats.

Police in Newtown, Connecticut, said the threat was made at about 9am on Friday and pupils were sent home for the day.

Lieutenant Aaron Bahamonde said there is a heightened level of anxiety in the town on the anniversary and the school superintendent decided to cancel remaining classes.

It is unclear whether the alert was related to bomb threats made nationwide on Thursday.

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

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

Authorities said the threat specifically referenced the anniversary, but police did not believe it was credible.

A 20-year-old gunman shot his way into the school in 2012 and killed the 26 victims before fatally shooting himself.

Connecticut governor Dannel P Malloy had ordered all state and US flags in the state to remain at half-mast, where they have been in honour of the late president George HW Bush.

"The unthinkable tragedy that occurred on this day will forever have an impact - not only here in Connecticut, but throughout the entire nation," Mr Malloy said in a statement.

"I think about these innocent, young children and generous, kindhearted educators every single day. I will always keep them in my prayers."

Additional reporting by Associated Press