Harrowing audio reveals frantic calls to 911 moments after Apalachee High School shooting that left four dead

POLICE in Georgia have revealed chilling audio from the 911 calls made moments after a shooter opened fire at Apalachee High School.

One of the cops captured on the recording can be heard shouting out "Active shooter!" as another calls in paramedics.

And one worried dad calls officials after hearing from his daughter, the school psychologist, hiding in a trailer with a student.

He tells the dispatcher: "My daughter just called, she’s in a trailer," as chaos unfolded on September 4.

"She’s trying to hide behind a desk with the kid that she has in there with her... but she’s upset because she can’t get the door locked."

One woman calls in to say: "My daughter calling me crying. Somebody go ‘boom, boom, boom, boom'."

The dispatcher tells her: "Ma'am we have officers out there, OK?".

In one recording clip the dispatcher asks for confirmation of the situation on the ground and an officer says "Correct. We have an active shooter at Apalachee High School."

Later on one is heard out of breath as he confirms the suspect is in custody and says "Roll EMS", referring the emergency medical services.

Colt Gray, 14, was arrested and charged with four counts of felony murder after allegedly carrying out Georgia's deadliest school shooting that killed four and injured nine.

Students Mason Schermerhorn, 14, Christian Angulo, 14, and teachers Richard Aspinwall and Christina Irimie were identified as those killed.

His dad Colin Gray, 54, was also arrested and charged after admitting to gifting his son the rifle that was allegedly used in the attack.

He was charged with four counts of involuntary manslaughter, two counts of second-degree murder and eight counts of cruelty to children.

Gray and his dad were interviewed by the FBI a year before the shooting when authorities received online threats of a possible attack.

His mum Marcee, 43, has insisted that she tried to warn the school before the shooting.

She received a text from him that read "I'm sorry, Mom", while she was visiting her dad three hours away from the school.

Marcee said she rang the school to warm them of an "extreme emergency", the Washington Post reports.

"I told them it was an extreme emergency and for them to go immediately and find [my son] to check on him," she said.

Gray is set to be tried as an adult but officials have said is not eligible for the death penalty if found guilty.

Timeline of Apalachee High School shooting

Below is a timeline of the shooting at Apalachee High School in Winder, Georgia, on September 4:

8:30 am - First period begins at AHS

9:45 am - Suspect Colt Gray leaves algebra class, according to his classmate

10:20 am - Police start to receive calls about an active shooter

10:23 am - Law enforcement officers are dispatched to school and arrive in minutes

10:45 am - AHS sends message to parents saying the school is in a hard lockdown

11:20 am - Students are evacuated to the football field

11:56 am - Barrow County Sheriff’s Office reports a suspect is in custody

2:13 pm - Georgia Bureau of Investigation confirms four people were killed and nine were hospitalized with injuries