Watch: Georgia school shooting suspect appears in court charged with four counts of murder

Watch from outside court where suspected Georgia school shooter, Colt Gray, 14, is set to be arraigned before a Barrow County Superior Court judge on Friday 6 September.

Gray has been charged with four counts of felony murder after a school shooting that killed four people and wounded nine others on Wednesday.

He would be tried as an adult, officials said.

Georgia state and Barrow County investigators say Gray used an “AR platform style weapon” - or semiautomatic rifle - to carry out the attack in which two teachers and two 14-year-old students were killed.

It remained unclear exactly how he came into possession of the weapon, but officials on Thursday arrested his father, saying he knowingly allowed his son to have the murder weapon.

Colin Gray, 54, was charged with four counts of involuntary manslaughter, two counts of second-degree murder and eight counts of cruelty to children, the Georgia Bureau of Investigation said.

Investigators have yet to comment on what may have motivated the first U.S. campus mass shooting since the start of the school year.

The shooting at Apalachee High School in Winder, a city of 18,000 some 50 miles northeast of Atlanta, revived both the national debate about gun control and the outpouring of grief that follows in a country where such attacks occur with some regularity.