Christian Helms, 15, who was facing trial as an adult on charges of attempted murder and three counts of transporting or possessing a destructive device, will plead guilty to two counts of the destructive device charges, The (Myrtle Beach) Sun News reported Tuesday.
Helms entered a so-called Alford plea on the attempted murder charge.
In such a plea a defendant asserts innocence but admits sufficient evidence exists for the prosecution to likely convince a jury to return a guilty verdict.
Police say Helms went into the Socastee High School office of Erik Karney, the school's resource officer, on Sept. 21 with a loaded gun and two pipe bombs in his backpack.
Helms, 14 at the time, shot at Kearney, police said, and was taken into custody at the school.
Helms' plea was entered after a jury was selected Monday, and Circuit Court Judge Thomas Cooper set sentencing for Wednesday.