A US school is undergoing a $48m renovation to help protect children in case of a mass shooting.
Fruitport High School in Michigan is making some of its hallways curved to cut down a potential gunman's firing range and installing cement blocks for children to hide behind.
Walls are also being erected in classrooms, where up to 40 students can hide so any killer cannot see them as they pass, and impact resistant film is being added to windows.