A Georgia county’s emergency call center was overwhelmed by calls on Sept. 4 about a school shooting at Apalachee High School that killed four people and wounded nine others, records released Friday by Barrow County show.

Local news organizations report many of the 911 phone calls were not released under public record requests because state law exempts from release calls recording the voice of someone younger than 18 years old. That exemption would cover calls from most of the 1,900 students at the school in Winder, northeast of Atlanta.

Calls spiked around 10:20 a.m., when authorities have said that 14-year-old suspect Colt Gray began shooting. Many calls were answered with an automated message saying there was a “high call volume,” WAGA-TV reported.

One man called 911 after receiving text messages from a girlfriend. He was put on hold for just over 10 minutes because of an influx of calls at the time of the shooting, The Atlanta Journal-Constitution reported.

“She hears people yelling outside, so I don’t know if that’s officers in the building or that’s — I don’t know,” he said, adding that she was eventually evacuated out of the school.

Other adults also called 911 after their children contacted them.

“My daughter calling me crying. Somebody go ‘boom, boom, boom, boom,'” one mother said. The 911 operator responded: “Ma’am we have officers out there, OK?”

Parents of students at an elementary school and middle school neighboring Apalachee also flooded 911 seeking information.

“Sir, my daughter goes to school next door to Apalachee. Is there a school shooter?” one caller asked.

“We do have an active situation (at) Apalachee High School right now,” the operator responded. “We have a lot of calls coming in.”

More than 500 radio messages between emergency personnel were also released Friday.

“Active shooter!” an officer yells in one audio clip while speaking with a dispatcher, CNN reported. Another officer responds, “Correct. We have an active shooter at Apalachee High School.”

The shooting killed teachers Richard Aspinwall, 39, and Cristina Irimie, 53, as well as students Mason Schermerhorn and Christian Angulo, both 14. Another teacher and eight more students were wounded, with seven of those hit by gunfire.

The Georgia Bureau of Investigation reported Thursday that the suspect rode the school bus on the day of the shooting with the assault-style rifle concealed in his backpack.

He then asked a teacher for permission to go to the front office to speak with someone, and when he received it, he was allowed to take his backpack with him, GBI said. He then went to a restroom, where he hid, and then eventually took out the weapon and started shooting, investigators said. A knife was also found on him when he was arrested.

According to investigators, the suspect enrolled at Apalachee High on Aug. 14, and between Aug. 14 and the day of the shooting, he was absent for nine days of school.

The family told CBS News that the suspect’s maternal grandmother had visited the school the day before the massacre to discuss the suspect’s alleged behavioral issues. 

The suspect has been charged as an adult with four counts of murder, and District Attorney Brad Smith has said more charges are likely to be filed against him in connection with the wounded. Authorities have also charged his father, 54-year-old Colin Gray, alleging that he gave his son access to the gun when he knew or should have known that the teen was a danger to himself and others.

The 13,000 students at Barrow County’s other schools returned to class Tuesday. The 1,900 students who attend Apalachee are supposed to start returning the week of Sept. 23, officials said Friday.