A campus watchman has a chance to stop gunman Nikolas Cruz before any blood is shed. But he doesn't do it.

Here’s a minute-by-minute look at those critical moments on Feb. 14, 2018.

To be sure, a number of teachers and police officers performed heroically. But an examination of the day’s events reveals that the Sheriff’s Office and school district were unprepared for the crisis.

A gunman with an AR-15 fired the bullets, but a series of blunders, bad policies, sketchy training and poor leadership helped him succeed. Information reported over 10 months by the South Florida Sun Sentinel reveals 58 minutes of chaos on campus marked by no one taking charge, deputies dawdling, false information spreading, communications paralyzed and children stranded with nowhere to hide.

Failures by the Broward County Sheriff’s Office and school district cost children and faculty their lives at Marjory Stoneman Douglas High School.

He recognizes Cruz as "Crazy Boy," the former student that he and his colleagues had predicted most likely to shoot up the school . He radios another campus monitor/coach, but he does not pursue Cruz and does not call a Code Red to lock down the school.

Security monitor Andrew Medina, an unarmed baseball coach, is riding in a golf cart and unlocking gates 20 minutes before dismissal. He sees Cruz walk through one of those unguarded gates with a rifle bag.

Geography teacher Scott Beigel is holding open his classroom door. As he ushers students in, Cruz shoots and kills him.

Cruz goes up the stairwell to the third floor , where about 20 people remain stranded in the middle of the hallway.

Cruz is on his way.

Rospierski and several students are stranded in the hall.

Social studies teacher Ernie Rospierski directs students back into classrooms, but his door locks behind him with his keys inside.

Students on the third floor are initially unaware there's a shooter in the building and are crowding the hallways because of the fire alarm. Now hearing the shots, they begin to run back toward classrooms.

He is still the only armed law enforcement officer on campus.

Instead of confronting the killer, he radios for a nearby intersection to be blocked off.

Deputy Peterson takes cover between Buildings 7 and 8 as Cruz prowls the second floor.

Cruz fires into two of 10 rooms, but no one is hurt.

Some teachers, probably hearing gunfire below, had taken steps to protect the children. They had covered the windows in classroom doors so a shooter could not see in. Some huddle children away from the gunman's line of sight.

Cruz heads up the west stairwell to the second floor but finds the hallway empty.

The carnage is astounding on the first floor, where Cruz kills 11 and wounds 13.

Feis, the campus monitor and football coach, opens the door to the west stairwell and comes face-to-face with Cruz. Cruz shoots him.

Over his police radio he says he can hear firecrackers or "possible shots fired" in Building 12. The statement conflicts with his later account: that he was unsure where the sounds were coming from.

Peterson finally arrives on the east side of Building 12. He draws his gun, but he fails to go inside the building.

Cruz shoots Hixon, who crawls to take cover in a nearby doorway. Cruz finds him about 30 seconds later and shoots him again.

Athletic director and campus monitor Chris Hixon is already at Building 12. He enters the double doors at the west end of the hall and runs toward Cruz.

Deputy Peterson and another campus monitor meet Medina, get into his golf cart, and drive toward Building 12.

Because the first 911 call is from a cellphone, it goes to the city of Coral Springs. But the Sheriff's Office handles police calls for neighboring Parkland, so the Coral Springs operator must waste precious minutes transferring the call to the Sheriff's Office.

At the same time, Deputy Scot Peterson – the school resource officer and the only armed lawman on campus – runs to meet with Medina, the campus monitor who first saw Cruz.

Instead of hiding in their classrooms, as they would during a Code Red, some students and teachers stream out of classrooms into hallways, as they would if facing a fire.

The repeated failures to call a Code Red become catastrophic when the shooting sets off a fire alarm.

The first 911 caller tells a Coral Springs operator that there's a shooter at the school. Gunshots are heard in the background.

Two security experts had advised Stoneman Douglas teachers and administrators to designate these safe spaces, but only two teachers in Building 12 did so. Most classroom corners that could have provided refuge were instead blocked by teachers' desks and other furniture.

The simplest of security measures could have saved lives. But the school district failed to require that classrooms have designated “hard corners” — areas where students could hide outside the line of sight of a gunman looking through a doorway.

Cruz stalks the first floor unchallenged. He enters no classrooms and shoots through the windows at people in his line of sight.

School district policies were insufficient and employees were uncertain who could order that the campus be locked down.

Taylor, the campus monitor, hears gunshots and races up to the second floor. He ducks into a janitor's closet . Taylor has a radio but does not call a Code Red.

Cruz fires his first shots, killing freshmen Martin Duque , Luke Hoyer and Gina Montalto in the hallway of the first floor.

There is no evidence that Feis, who has a radio, calls a Code Red.

McKenna runs from the building and informs Aaron Feis , a football coach and campus monitor, that there is someone with a gun.

The second chance to lock down the school is missed when freshman Chris McKenna enters the first-floor stairwell and sees Cruz loading his gun.

Taylor turns around, later telling investigators he intended to use stairs at the opposite end of the hallway to intercept Cruz on the second floor.

David Taylor, the campus monitor who was alerted by Medina, walks into the first-floor hallway toward Cruz, who goes into the stairwell. At that point, Cruz has yet to pull his gun from the carry bag.

Medina is the first of three school employees who fail to call for a school lockdown after learning a gunman is on campus.

Medina shouldn’t have been in that job – school investigators had recommended he be fired for sexually harassing students , but district administrators overruled them.

He stops near the football field, about 1,000 feet from Building 12, to block traffic.

More deputies hang back — even though they can hear the gunshots

Deputy Peterson, over his radio, orders a school lockdown instead of ordering deputies toward the building. He remains safely outside.

Cruz shoots at the glass, targeting students and teachers as they flee across the campus below, but the glass won't break and no one on the ground is hit.

Unable to get into the stairwell, Cruz heads to a nearby teachers’ lounge.

It's now been nearly four minutes since Cruz started shooting, and deputies Peterson and Kratz are still not going toward Building 12.

By the time he is done, Cruz kills six and wounds four on the third floor. None of the dead are in classrooms.

Two of the students, Jaime Guttenberg and Peter Wang , are hit. Wang dies in the hallway and Guttenberg in the stairwell, but others get away as Rospierski holds the door closed from inside the stairwell to keep Cruz from advancing.

Rospierski flees with 10 students toward a stairwell as Cruz fires down the hall.

Cruz kills senior Meadow Pollack and freshman Cara Loughran outside a locked classroom; they die huddled together. Cruz shoots senior Joaquin Oliver outside a locked bathroom.

They have nowhere to hide from Cruz and his bullets.

An earlier decision to lock restrooms because students were vaping in them now traps those who try to find refuge on the third floor.

Deputy Kratz adds to the confusion with a radio broadcast. He says he hears shots by the football field northwest of Building 12 – raising questions about where the shooter is.

Bonner, who is unarmed, backs away from the scene in his cart.

Campus monitor Elliott Bonner calls the alert after driving his golf cart to the southwest corner of Building 12, where he sees Feis' body and hears gunshots.

Cruz’s assault, which would span 5 minutes and 32 seconds from first shot to last, is half over when someone finally declares a Code Red.

All of them hear gunshots as Cruz continues to shoot in the teachers' lounge but remain near their cars just off campus .

Four more Broward deputies arrive at the school, stopping north of the campus.

Broward Sheriff Scott Israel later reveals that he personally changed department policy to say that deputies “may” instead of “shall” rush in.

Since Columbine, officers are taught to rush toward gunshots and neutralize the killer. But the first Broward deputies don’t rush in.

Miller is among eight armed deputies now at the school. All hear gunshots, but none rush to Building 12 to look for the killer.

Rather than rush in, he takes time to put on his bulletproof vest and hide behind his car on Holmberg Road, not going on the radio for 10 minutes.

Sgt. Brian Miller stops north of Building 12. He is the highest-ranking officer on the scene but fails to take control or move from his car.

Deputies dawdle as shots fired The last five gunshots can be heard on the body cam of Deputy Josh Stambaugh. After parking at Holmberg Road near the scene of the shooting, he retrieves his bulletproof vest from the trunk, puts it on and takes cover behind his car. After five minutes there, he gets into his car and drives to the other end of the campus to take a position on the Sawgrass Expressway overlooking the school. The final shot Cruz fires, from inside the teachers’ lounge, can be heard at 2:27:10 p.m.

Cruz escapes, cops have no idea Cruz takes off his rifle vest, drops his AR-15 in a stairwell, heads down the stairs, darts out of the building and runs across campus — all while police think he's still inside.

Cops protect themselves A few seconds later, Peterson, still hiding southeast of Building 12, tells deputies over the radio to stay at least 500 feet away from the building. / The warning is one of at least two times a Broward deputy urges another officer to protect themselves, not confront the killer. Though police officers since Columbine have been trained to immediately confront the killer, some Broward deputies at the Parkland massacre would later struggle to recall when they last had active shooter training or details of what they learned.

Fooled by video delay The surveillance cameras in the school are not monitored in real time. Assistant Principal Jeff Morford and school security officer Kelvin Greenleaf enter the school's camera room to rewind and review surveillance video, but deputies don’t realize the footage is delayed 20 minutes. Morford relays information about Cruz's whereabouts to Peterson and other school officials. Cops, believing the video is live, continue searching for Cruz in the building — delaying aid to injured students.

Sheriff's commander overwhelmed Broward Sheriff's Capt. Jan Jordan, head of the Parkland district, arrives at the school's administration building and is quickly overwhelmed as she tries to coordinate officers. The faltering radio system frustrates her. She spends her first seven minutes at the school in the administrative building and then goes to a nearby car to try again with the radio system. She eventually moves to another area near Building 12, where she takes cover behind a car to meet with officers.

No command post – again The Sheriff’s Office fails to immediately set up a command post – just as the agency failed to do after a mass shooting at the Fort Lauderdale airport the year before. A Broward deputy asks that the command post be set up to help control the response, but it isn't done for another half-hour. /

Coral Springs police officers rush in The shooting has been over for five minutes before any police officers enter the building. Four Coral Springs officers enter through the west doors, where they see Chris Hixon shot. Two officers pull Hixon out of the building and onto a golf cart. He will not survive. The Coral Springs officers later tell investigators their training was clear – run toward the gunfire. Coral Springs Officer Raymond Kerner, the school resource officer at nearby J.P. Taravella High School, would tell investigators: “Basically, what we’re trained to do is just get right to the threat as quick as possible and take out the threat because every time you hear a shot go off it could potentially be a kid getting killed or anybody getting killed for that matter.”

Commander fails to act Capt. Jordan orders that a perimeter be established around the school – a misguided approach when facing an active shooter. Before Columbine, setting up a perimeter was standard. After Columbine, police were trained to rush toward the gunshots. Jordan does not establish a command post or call for officers to go find the shooter. /

More bad information from Peterson Deputy Peterson adds more bad information to a chaotic scene. Still sheltering by a building, he tells a Coral Springs officer the shooter is on the second or third floor. In reality, Cruz has been out of the building for more than six minutes.

First deputy inside Broward Deputy William Hanks enters Building 12 through the west doors, one minute and 45 seconds after Coral Springs officers first entered.

More officers rush in About 18 officers, the majority from Coral Springs, head into the east side of Building 12 about this time. More sheriff’s deputies begin to enter the building as well.

"Dream-like" Without a command post established, deputies remain confused about who is in charge. Broward Lt. Stephen O'Neill takes command of the response early on, recognizing the lack of direction from supervisors. He later says Jordan had a “dream-like” nature to her speech and that she “was not engaged with the problem." O'Neill works to keep the roads by the school clear for more responding vehicles and to create an area where officers can stage during the response. But doing so also slows the police response into Building 12.

Evacuation of Building 12 Officers begin a mass evacuation of survivors from Building 12.

Gunman long gone Assistant Principal Morford, in the video room, broadcasts over school radios that Cruz is leaving the third floor and headed to the second floor. Officers believe Morford is watching the video in real time, but in fact Cruz has already walked to a nearby Walmart and ordered a drink at Subway. Video from Sgt. Richard Rossman’s body cam shows officers relaying Cruz’s movements over the radio and Assistant Principal Winfred Porter, outside with the police, incorrectly confirming the video is live.

Cruz on the move Cruz leaves Walmart and heads to a nearby McDonald's. He stays there a minute and then leaves.

Officers reach third floor Three Coral Springs officers reach the third floor and find Cruz's gun, vest and the body of Jaime Guttenberg. Deputies in Building 12, still believing the gunman is inside, are experiencing radio problems. Body cam video records one deputy saying he needs to go outside to use his radio.

The truth about the video Cops finally learn that the surveillance video is delayed. Sgt. Rossman has known it for seven minutes — at a time when every minute was critical — but he has not broadcast it over the radio until now. /

Hiding for 48 minutes School Resource Officer Peterson leaves the spot where he has remained sheltered for nearly 48 minutes, watching as other officers enter the building.

Final classroom entered Almost an hour after the shooting began, officers enter the final room in Building 12.