Several people were injured in a shooting at Apalachee High School in Winder, Georgia, on Wednesday morning, according to Barrow County Sheriff Jud Smith.

One suspect has been arrested, the sheriff’s office said.

According to the sheriff’s office, details about the number of victims and their conditions are not yet available.

Senior Sergio Caldera, 17, said he was in chemistry class when he heard gunshots.

“My teacher goes to open the door to see what’s going on. Another teacher comes running in and tells her to close the door because there’s an active shooter,” Caldera told ABC News.

He said his teacher locked the door and the students ran to the back of the room. Caldera said they heard screams from outside as they “huddled together.”

At one point, Caldera said, someone banged on the door of his classroom and yelled “open up!” several times. When the knocking stopped, Caldera said he heard more gunshots and screaming.

He said his class was later evacuated to the football field.

Apalachee High School has been “approved to close” and all other schools in Barrow County have been placed on “soft lockdown,” according to the Barrow County School District.

“The Barrow County Sheriff’s Office says this is for the safety of everyone at this time. Please do not attend your child’s school at this time. We are unable to release students during a lockdown,” the school district said in a statement. “We will let you know as soon as BCSO says everything is clear for dismissal.”

Winder is located approximately 45 miles outside of Atlanta.

President Joe Biden has been briefed on the shooting. “His administration will continue to work with federal, state, and local officials as we receive more information,” the White House said.

Agents from the FBI and the Georgia Bureau of Investigation are on the scene.

Attorney General Merrick Garland said, “I am devastated for the families affected by this terrible tragedy. The Department of Justice stands ready to provide any resources or support.”

Georgia Governor Brian Kemp said he is “praying for the safety of those in our classrooms, both in Barrow County and across the state.”

In Atlanta, authorities will “increase patrols around schools” on Wednesday “out of an abundance of caution,” Atlanta Mayor Andre Dickens said in a statement.

“My prayers are with the high school students, staff and families affected by the senseless act of violence in Winder,” Dickens said.

This is a developing story. Check back for updates.

ABC News’ Josh Margolin and Miles Cohen contributed to this report.