The gunman who murdered three women at a Pennsylvania gym posted a chilling diary on the internet in which he seethed with anger and frustration towards the opposite sex.

A gunman walked into a US exercise class, turned off the lights and shot three women dead before killing himself.

A woman who disappeared as a teenager 10 years ago had been living with a middle school security guard who did not allow her to leave his home for several years, police in Pennsylvania said.