CHARLOTTE, N.C. -- Friday morning, the Charlotte-Mecklenburg Police Department released the 911 calls from the deadly UNC Charlotte shooting.

MORE: Full Coverage of the UNCC Shooting, including first-hand accounts, tributes to the victms, lawmaker responses and more.

Authorities say that 32 out of the 48 calls placed were received within 16 minutes. The shooting suspect, Trystan Terrell, is accused of opening fire in a UNCC classroom, killing two and injuring four others.

Police initially responded to an active shooter call on South Library Lane in the Kennedy building. The campus was placed on lockdown.

Listen to some of the 911 calls below:

Note: Some of the audio may be disturbing to some listeners and discretion is advised.

Terrell has been charged with two counts of murder, four counts of attempted murder, four counts of assault with a deadly weapon with intent to kill and possession of and discharge of a firearm on educational property.

The two students killed were 19-year-old Ellis Parlier of Midland and 21-year-old Riley Howell of Waynesville. The four shot are 19-year-old Drew Pescaro and 20-year-old Sean DeHart of Apex, 20-year-old Rami Al-Ramadhan from Saudi Arabia and 23-year-old Emily Houpt from Charlotte. As of Thursday, DeHart had been released from the hospital.

Howell has been hailed as a hero as witnesses say he was killed trying to stop the suspected shooter, Terrell. "He didn't run, he didn't hide, he fought," CMPD police chief Kerr Putney said at a press conference earlier this week.

All the 911 calls from Tuesday's shooting can be found here.