(CNN) -- The 911 calls started pouring in at 2:23 p.m.
Former student Nikolas Cruz, 19, was roaming the halls of Marjory Stoneman Douglas High School, gunning down terrified students using a semiautomatic AR-15 rifle. He fatally shot 17 people before discarding the rifle and blending in with fleeing students, authorities said. For 78 minutes, from the time the first 911 call came in to his arrest, officers from the Broward County Sheriffs Department mobilized to find him. Here are some of their communications during the search, all are direct quotes with some edited for clarity.
The gunman fled shortly after the shooting. Officers quickly identified him:
Officer: "White male, burgundy shirt, wearing a black hat and either long black pants or shorts. He mixed in with a group of students who were running westbound ..."
Officer: "I'm being told, advised by the employees that it should be a student: Nikolas Cruz, Nikolas Cruz, who came in on campus with a backpack."
Dispatch: "Nikolas Cruz, is that confirmed?"
Officer: "I'm getting that from the baseball coach -- they were told it was Nikolas Cruz."
Too terrified to open doors
Students called 911 before opening doors:
Dispatch: "Student in classroom 1255 says somebody's pushing on her door -- is that a police officer? Any units pushing on 1255?"
Officer: "Yes, yes, 1255, that's going to be us."
Dispatch: "You want them to open it or do you want me to tell them to stand down?"
Voice: "Tell her to open her door, have her open her door right now!"
Dispatch: "All right, I'm telling her right now."
Calls for extra officers
As the clock ticked, officers expanded search area:
Officer: "Anybody who's not doing anything right now, I need to spread this perimeter out. ... Our east perimeter is fine, just start getting units down to the west and lock down Walmart!"
Officer: "There's a lot of units here on scene, if they're not doing anything they need to get to the perimeter -- we have more than enough units on scene."
Officer: "Any units that have access to a computer or can open media that they can look up an Instagram account, it's going to be Cruz_Nikolas -- I'm advised that might be the suspect -- he has a recent post holding a gun."
Officer: "Anybody evacuating students, I don't need them going west -- they should be going east toward school buses. East toward school buses if you're evaccing students."
Search for shooter's photo
Students at the scene provided details on the shooter:
Officer to dispatch: "I need a suspect's name again -- I'm going to talk to a student who may get a picture."
(Dispatch repeats name)
Officer: "I just talked to a student, I know somebody's looking for a photo. He should be a ginger, red hair with freckles. Always wears a hoodie, was part of the ROTC program. He's about 5'8."
Officer: "I'm being advised by ROTC students that he was kicked out last year. We're still looking for a photo -- he worked at a Dollar Store on Magnolia. Last name spelling is C-R-U-Z."
All student evacuees checked
There was fear shooter could be among rescued students:
Officer: "Someone checking the IDs of those kids before they get up and leave the area?"
Officer: "Attention all units, be advised -- a repeat of the last instruction -- juveniles being loaded onto the buses are going to park. The IDs need to be checked of the juveniles before they get on the buses. Make sure that Nikolas Cruz isn't part of this group."
False sightings, unattended bags
As the search progressed, there were false reports of his sighting:
Dispatch: "Shooter in building, 1305, science building, first floor."
Officer: "That's a negative on 1305"
Dispatch: "We're being advised of a report of unattended bags at the east side of the school ... I'm being told to pass that on to you, that there's an unattended backpack on the east side of the school."
Officer: "Leave all unattended bags alone, just leave them alone. We'll sweep them ... later."
The family he lived with provided crucial information:
Officer: "I just spoke with Nikolas' father. He said he spoke with him and he said he was at a McDonald's by the school -- I'm trying to see what that address is ..." (Officers provide address for the closest McDonald's)
Officer: "I'm talking to Nikolas' caregiver. We need some units to go to his house ... He's got a safe with guns, he doesn't know if his wife is OK."
Officer: "I've got bad radio service, I've got the mom. She's 10-4. (OK) I'm going to need a couple extra units out here to secure the house. There's possibly a male in the house, not the suspect. We're trying to talk him out."
'Nikolas Cruz is in custody'
78 minutes after the 911 calls came in, Cruz was arrested
Officer: "We have the suspect detained."
Officer: "Can we get a positive identification that Nikolas Cruz has been detained?"
Officer: "10-4 -- confirmed that Nikolas Cruz is in custody."
Officer: "I'm ... here at the apprehension scene. The clothing is identical. We are going to need homicide or whoever is going to be working this here on scene ASAP, especially when they're going to do the one on one. We need investigators."
Officer: "Also ... we'll want to send some dogs this way to do article search, you want to get them out of staging, and get them over this way?"
Officer: "We're gonna get investigators here ... they're going to show up and then start doing article searches to see if he dropped anything in this neighborhood."
After arrest, there were concerns of another gunman:
Officer: "I just want to confirm: we have no intel of any other suspects, just the one?"
Dispatch: "Any units have additional information about any potential additional participants involved in this incident?"
Officer: Positive ID. That's the only one.
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