LONDON—Police raided homes and properties of dozens of suspected pedophiles, arresting 76 people—including a retired teacher and a scout leader.

Officers from 40 forces working under the direction of the Child Exploitation and Online Protection Center executed 141 warrants. The warrants included offenses relating to the possession and distribution of indecent images of children.

Kate Fisher, an analyst at the center, says the images being downloaded by pedophiles are increasingly becoming more extreme, sadistic and violent. They are also featuring increasingly younger children.

Among those arrested by police were a referee, a pathologist, a firefighter, and a computer programmer.