A shooting at a high school about 45 miles outside Atlanta on Wednesday morning has left multiple casualties, officials in Barrow County said, adding that a suspect was in custody.

A representative for Grady Memorial Hospital in Atlanta said that it had received one gunshot wound victim from Apalachee High School in Winder, Ga.

In a statement shared with Atlanta News First, a local television news outlet, the Barrow County Sheriff’s Department said that details on the number of casualties — which can include dead or wounded — were not immediately available.

Several schools in Georgia were under lockdown on Wednesday morning, the fifth full week of school, after gunfire was reported at the high school about 10:20 a.m., according to a spokeswoman for the school and the sheriff’s department.

The F.B.I. was also on the scene, and the Georgia Bureau of Investigation said on social media that an investigation was continuing.

Footage from WSB-TV, a local news outlet, showed parents lining up in cars to pick up their children, many of whom had gathered on the high school’s football field.

“We are aware of a situation at Apalachee High School where gunfire was reported,” a spokeswoman for the Barrow County School System said. She said that the high school had been cleared to release students, but several other schools remained under lockdown.

Gov. Brian P. Kemp said on social media that he was directing all available state resources “to respond to the incident” at the school in Barrow County.

The White House said in a statement that President Biden had been briefed on the shooting and that the administration would continue coordinating with federal, state, and local officials.

This is a developing story. Check back for updates.