A former Florida student recalled on the stand Tuesday the haunting moment he encountered Nikolas Cruz in the stairwell moments before the teen gunman opened fire, massacring 17 people at Marjory Stoneman Douglas High School in 2018.

Then-freshman Christopher McKenna told jurors that he had left his classroom for a bathroom break when he ran into two classmates in the halls. 

"I saw Martin and Luke and I high-fived Martin. I walked by him like it was normal," said McKenna, who didn’t specify whether he was referring to Luke Hoyer, 15, and Martin Duque Anguiano, 14, who were murdered minutes later.

McKenna then came upon Cruz, 23, in the stairwell, wearing a backpack, black pants and clutching a rifle. McKenna was the first person Cruz saw when he entered the building. 

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Parkland Florida mass shooting crime

Marjory Stoneman Douglas High School shooter Nikolas Cruz is shown at the defense table during jury selection in the penalty phase of his trial at the Broward County Courthouse in Fort Lauderdale, Fla., on Tuesday, June 28, 2022.  (Amy Beth Bennett/South Florida Sun-Sentinel via AP, Pool)

"[Cruz] said to me, ‘Get out of here. Things are about to get bad,’ McKenna, maintaining his composure, told Broward County jurors of the Feb. 14, 2018, rampage. "I walked through the double doors. I sprinted as fast as I could."

After McKenna exited the school building he heard gunfire. About three dozen relatives of the victims were in court and many grew tearful during the testimony.

Cruz pleaded guilty in October to the premeditated murder of 14 students, an athletic director, a teacher and a coach. He was a 19-year-old expelled student at the time.

Diagram showing details of Parkland school shooting

Graphic gives details of the Marjory Stoneman Douglas High School shooting. (Associated Press)

The sentencing trial will determine whether Cruz gets life in prison or the death penalty. Cruz’s lawyers have pointed to his history of mental illness in arguing for life in prison.

Two other former students who were wounded in the shooting described the moment Cruz opened fire and the devastation in the classroom.

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William Olson recalled hearing loud noises then noticing he was injured. "I realized there’s blood all over me," he said. Jurors were show photographs of the injuries on his arms.

Marjory Stoneman Douglas High School shooter Nikolas Cruz tucks his sweater in while waiting for prospective jurors to enter the courtroom during jury pre-selection in the penalty phase of his trial at the Broward County Courthouse in Fort Lauderdale, Fla., on Tuesday, April 26, 2022. Cruz previously plead guilty to all 17 counts of premeditated murder and 17 counts of attempted murder in the 2018 shootings. (Amy Beth Bennett/South Florida Sun-Sentinel via AP, Pool)

Marjory Stoneman Douglas High School shooter Nikolas Cruz tucks his sweater in while waiting for prospective jurors to enter the courtroom during jury pre-selection in the penalty phase of his trial at the Broward County Courthouse in Fort Lauderdale, Fla., on Tuesday, April 26, 2022.  (Amy Beth Bennett/South Florida Sun-Sentinel via AP, Pool)

Another student in the same classroom, Alex Dworet, took the stand next and said after the gunfire he felt a hot sensation on the back of his head.

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"I remember feeling [blood] trickling down the back of my head and onto my chest, and then I touched the back of my head and my hand was all bloody," he testified.

He surveyed the classroom and saw Alex Schachter, 14, dead and hunched over his desk.

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"I saw a pile of blood forming under him," he said of Schachter. "I saw his body, not spasming, but more like trying to take his final breaths and at that moment it started getting more real."