A school in the United States has spent $48 million redesigning its buildings with curved corridors, hiding places, and cement barriers in a bid to thwart mass shooters.

The project at Fruitport High School in Michigan is aimed at reducing casualties in the event of an attack by hampering the sight lines available to a gunman in corridors.

Cement barriers are being installed in hallways for pupils and teachers to take cover. Classroom windows looking on to hallways are being covered with impact-resistant film.

Each classroom will also have a corner, called a "shadow zone," that is not visible from the hallway.

And school administrators will be able to lock all the doors in the building by pushing a button.

Bob Szymoniak, the school superintendent, said: "This building will be the safest, most secure building in the state of Michigan when it opens.

"These are going to be design elements that are just naturally part of [school] buildings going into the future."

He added: "If I go to Fruitport High School and I want to be an active shooter, I'm going in knowing I have reduced sight lines. It has reduced his ability to do harm."

The changes will be unveiled in December and could lead to other schools across the US taking similar measures.