An orphaned 19-year-old with a troubled past and an AR-15 rifle was charged with 17 counts of premeditated murder on Thursday morning after being questioned for hours by state and US federal authorities following the deadliest school shooting in the country in five years.

In America, a 16-year-old girl has died after a fight broke out - reportedly over a boy - in a high school toilet in the US state of Delaware.

An Australian high school has sparked a national furore by allowing pupils to wear boy or girl uniforms, regardless of gender.