A teenager is believed to have shot and killed his father before going to a nearby elementary school in South Carolina and wounding two children and a teacher.
A teacher called 911 to report a gunman on Wednesday afternoon (local time) and police arrived within seven minutes at Townville Elementary School in Anderson County, northeast of Atlanta.
One of the six-year-old children shot was in critical condition and in surgery at Greenville Memorial Hospital, Scott Stoller, Anderson County's director of emergency services, told the Anderson Independent Mail.
Juana Slade, spokeswoman for AnMed Health Medical Center, said they were treating one adult woman and a boy. Both were in good condition.
Authorities said the dead male victim is believed to be 47 years old. Both students were boys and the teacher was an adult woman.
One student was shot in the leg and the other was shot in the foot, and the teacher was shot in the shoulder, authorities said.
The shooter and all victims were white.
Anderson County Sheriff's Office Captain Garland Major did not know the relationship between the shooter and those injured at the school.
He said a handgun was used but would not say where exactly the shooting occurred or how the shooter entered the school.
Governor Nikki Haley is due to meet with law enforcement officials in the area this evening, Anderson County emergency services director Taylor Jones said.
The incident was the latest in a series of shootings at US schools that have fuelled the debate about access to guns in America.
Armed officers guarded students as they were moved from the school and taken by bus to a nearby church, local media said.
Television images showed police swarming the school, with some officers on the roof while others moved around the building.
Jamie Meredith, whose daughter is in kindergarten at Townville Elementary, told WYFF News she panicked after getting word of the shooting.
Her daughter is OK but described a scene of scared and crying children.
"I'm just scared," the woman, who was not identified, said through tears as she was interviewed by WYFF.
"I don't even want her to go to school now."