Moments before images of frightened students captured the scene, audio from the emergency radio system recorded its chaos.
But mixed into the high octave chorus of emergency response, you can hear unexpected challenges police and fire rescue crews in Broward County couldn't hear coming.
"Bravo 2-3, we're having trouble communicating," said an officer in an excerpt pulled off of broadcastify.com, a website that tracks and records radio scanner traffic among emergency crews.
The radio system police and rescue crews used to communicate was overloaded leaving crews unable to talk to each other during some of the earliest moments of response from the Broward County high school shooting.
"Attention all units, keep your radio traffic to an absolute minimum due to overload," a dispatcher can be heard saying.
"Be advised our radio might go down."
Bruce Moeller is a former Florida Fire Chief and City Manager, today he's a public safety consultant with Fitch & Associates.
"There are a number of factors that can drive it, but generally what it is is the radio channel is just too busy because there are too many people trying to get on a single radio channel at a single point in time," he said.
It's a problem experts on the technology side see often with radio systems that aren't reliable due to age.
While rural counties are typically most often plagued with an outdated system, we found upgrades happening around the state including in Pinellas County, Pasco County and even Broward County. The county's aged emergency radio system made headlines about a year ago after officers responding to the Fort Lauderdale airport shooting had trouble communicating. The county's system is now undergoing a $60 million replacement.
But even the most powerful systems, Moeller says, will have its challenges when a crisis occurs and everyone tries to respond.
"When you have a circumstance such as what happened recently the incident goes from 0-150 mph within about 2-3 minutes and adjusting the system to adapt to that is the greatest challenge."