By Rosa Flores, Mayra Cuevas and Nicole Chavez, CNN
(CNN) -- As a gunman killed petrified students and staff members at Marjory Stoneman Douglas High School last month, officers outside were having difficulty sharing crucial information with each other.
A timeline released Thursday by the Broward County Sheriff's Office reveals the chaos surrounding law enforcement's response to the Valentine's Day shooting Parkland, Florida. Using radio traffic, 911 calls and security video, it details officers' inability to communicate with each other and confusion as they tried to locate the shooter, later identified as 19-year-old Nikolas Cruz.
The release of the detailed timeline of law enforcement operations comes days after Florida Gov. Rick Scott ordered an investigation into the response to the deadly shooting at the Parkland school.
Confusion among agencies
According to the timeline, dozens of calls poured in as law enforcement officers from two different agencies descended on the scene and discovered their radios didn't work correctly.
Also, officers with the Broward County Sheriff's Office and the Coral Springs Police Department were unable to communicate with each other when attempts to merge radio traffic from the two agencies into a common radio channel failed, according to the sheriff's office.
This delayed the exchange of vital information between the agencies, like a description of Cruz and the weapon he was using.
"White male with ROTC uniform burgundy shirt," a Coral Springs police officer said over radio. "Last seen in the three-story building (12), north parking lot."
But at the same moment, a deputy with the sheriff's office was asking for information on the shooter's location. Another officer responded, "We don't know, but we're heading in the building, in front of the 13 building, building 13."
Seconds later, a sheriff's deputy said one victim reported the shooter was carrying "an AR15 or AK47." A minute later, a Coral Springs officer asks for any information about the weapon used in the shooting.
The sheriff's office uses the radio system maintained by Broward County, the timeline said, which is "nearing its end of life," a statement released alongside the timeline said, and the system "can become impaired when an excessive number of users access the system."
At some points, users may have been unable to transmit or receive any messages at all, the statement added.
'My school is being shot up:' What happened that day
'A lot going on'
School resource officer Scot Peterson, who officials say waited outside the school building as the shooting unfolded, initially oversaw his colleagues' response to the shooting.
In the first 10 minutes after gunfire erupted, Peterson ordered officers to shut down the street intersection in front of the school, began a lockdown and alerted officers of the location of possible gunfire.
"For the initial stages of the event, Peterson is the eyes on the ground so it's appropriate for him to relay that information and direct responding personnel," Col. Jack Dale told CNN.
He may have slowed down the response by ordering officers to stay at least 500 feet away from the building, according to the audio recordings.
The agency's active shooter policy calls for deputies to interrupt the shooting and search for victims when there's a ceasefire.
Broward County Sheriff Scott Israel had said Peterson should have gone inside the building and killed the gunman.
Peterson's attorney has said he did not enter the school because he believed the shooting was coming from outside the school buildings.
But the updated timeline and dispatch audio contradicts that assertion.
At 2:25 p.m., or about four minutes into the shooting, a deputy says over the radio "some students thought it was firecrackers, but we're not sure, by the football fields."
Peterson responds "We also heard it's by, inside the 1200 building."
"That contradicts the statement his attorney gave, that he didn't know where the shots were fired. After multiple gun shots you would have to know where the shots were coming from," said the head of the Broward County Sheriff's Deputies Association Jeff Bell.
CNN's calls to Peterson's attorney were not immediately returned. Peterson resigned after he was suspended without pay.
Broward County Sheriff's supervisor Capt. Jan Jordan arrived later to oversee the operation.
"I know there is a lot going on. Do we have a perimeter set up right now and everybody cleared out of school?" Jordan asked on the police radio.
"That's a negative," a dispatcher replied.
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