A 15-year-old in South Carolina has been sentenced to serve six years in prison for charges connected to a Columbine-style attack that authorities said he had intended to carry out at his school.

Christian Helms pleaded guilty to adult charges of attempted murder and carrying pipe bombs to a school in Socastee, near Myrtle Beach.

Evidence showed that the then 14-year-old Helms brought a .38-caliber revolver to school last September and fired it at a school police officer, wounding him, Horry County Assistant Solicitor Alicia Richardson said.

"He had a hit list," Richardson said. "There were 20-something people on it."

Police found bomb-making equipment at his home and writings that indicated he idolized previous school shooters at Columbine High School in Colorado and Virginia Tech, Richardson said.

She said the teen also had made videos of his homemade bomb detonations and posted them on YouTube prior to the school attack.

Helms talked about being bullied extensively at school, Richardson said.

"He talked about being teased for his red hair," she said.

Doctors who testified in his defence said the teen suffered from depression, conduct disorder and attention deficit hyperactivity disorder, she said.

Helms had faced up to 30 years in prison on the attempted murder charge and two to 15 years each on two bomb charges.

He was sentenced to serve five years of probation after his release from prison.