Gwinnett police Cpl. Edwin Ritter said the officer was directing traffic at Lanier High School in Buford when he was hit shortly before 7 a.m. Wednesday.
Ritter tells The Atlanta Journal-Constitution that the officer suffered serious injuries in the accident.
Gwinnett schools spokeswoman Sloan Roach identified the injured officer as Rolando Jimenez. She said he has been with the school system police since 2001.
Ritter said charges are pending against the driver of the vehicle that struck Jimenez.