Parkland Marjory Stoneman Douglas High School teachers recall horror moments during 2018 massacre

Marjory Stoneman Douglas High School shooter Nikolas Cruz. Photo / AP

Teachers gave heart-wrenching testimony on Wednesday in the penalty trial of Nikolas Cruz, with one recalling how a boy in her Holocaust studies class correctly answered a question seconds before he became one of 17 people murdered during the school shooter's rampage four years ago.

Ivy Schamis, then a teacher at Parkland's Marjory Stoneman Douglas High School, was leading students through a discussion about the 1936 Olympics in Nazi Germany when star swimmer Nick Dworet correctly responded that Adolf Dassler founded the Adidas shoe company. He then added that Dassler's brother founded the rival Puma brand.

It was then that they heard the initial gunshots in the first-floor hallway of the three-storey building, and Cruz began firing his semi-automatic rifle through the glass on her classroom door near where he entered.

"It was really seconds later that the barrel of that AR—15 just ambushed our classroom," Schamis testified, wiping her eyes with a tissue.

"It came right through that glass panel and was just shooting everywhere. It was very loud. Very frightening. I kept thinking about these kids who should not be experiencing this at all."

She said the students scrambled to find safety behind furniture, but didn't panic and acted with bravery and maturity as they waited to be rescued.

Three students were wounded in her class and two were killed: Dworet and Helena Ramsay, both 17.

In this February 14, 2018 file photo, students hold their hands in the air as they are evacuated by police from Marjory Stoneman Douglas High School in Parkland. Photo / AP

When shown their portraits, she began to weep.

"That's my girl, Helena Ramsay," she said. "Nicholas Dworet, handsome boy."

Dworet's brother Alexander was grazed by a bullet in a classroom across the hall, where three students were killed and several more wounded.

Cruz, 23, pleaded guilty in October to 17 counts of first-degree murder for the February 14, 2018, massacre. The jury must decide if the former Stoneman Douglas student should be sentenced to death or life without parole for the nation's deadliest mass shooting to go before a jury.

The trial is expected to last through at least October.

Nine other gunmen who killed at least 17 people died during or immediately after their shootings, either by suicide or police gunfire.

The suspect in the 2019 slaying of 23 people at a Walmart in El Paso, Texas, is awaiting trial.

Schamis' testimony was followed by that of Ronit Reoven, who was lecturing her advanced psychology class about Sigmund Freud when Cruz started firing into her neighbouring classroom, also through the door's window.

"There were multiple gunshots," she said. "They were incredibly loud. BOOM BOOM BOOM BOOM BOOM! I froze for a moment and the students jumped out of their seats. Of course, they were startled and scared."

Reoven said she and the students crouched on the floor around her desk and wounded students were moaning and crying.

Law enforcement officers block off the entrance to Marjory Stoneman Douglas High School in Parkland. Photo / AP

She used a blanket that normally covered her coffee machine as a tourniquet to stop the bleeding from a boy's arm. Another boy used a jacket to staunch the bleeding from a girl's chest. A girl shot in the knee appeared to be stable. But 16-year-old Carmen Schentrup was lying facedown in a pool of blood.

"I knew that she was probably gone," Reoven said.

On the third floor, Stacey Lippel was teaching creative writing and Ernest Rospierski was supervising study hall when Cruz's shots on the first floor triggered the fire alarm. Not realising a shooting was happening below them, they led their students into the hallway to evacuate.

That's when screaming students began coming back up the stairwell and they could hear gunshots.

Lippel said she and the teacher from the neighbouring room, Scott Beigel, quickly reopened their doors and started getting students back inside. It was then that Cruz emerged from the stairwell, "splaying the rifle back and forth, shot after shot after shot", she said.

"It never stopped."

Lippel said she got inside her room and closed the door, but Beigel was fatally shot.

Beigel's student, Veronica Steel, testified that his body kept the door from closing, leaving the students in the room fearful Cruz would come inside.

"It was scary. We didn't know what to do," she said.

Rospierski's head and hip were grazed by bullets, but he helped students who had gathered in the alcove outside his classroom flee down a stairwell when Cruz briefly stopped shooting.

Surveillance video played for the jury shows that two wounded students, 18-year-old Meadow Pollack and 14-year-old Cara Loughran, remained behind, lying on the floor.

Cruz killed them with a second blast. He then killed 17-year-old Joaquin Oliver, who was lying wounded in front of a restroom.

An early morning fog rises where 17 memorial crosses were placed for the 17 students and faculty killed in the shooting at Marjory Stoneman Douglas High School. Photo / AP

Two students in the fleeing group, 14-year-old Jaime Guttenberg and 15-year-old Peter Wang, were hit just before they reached the stairwell door and potential safety. Both died, Wang after Cruz shot him with a second volley.

When jurors eventually get the case, they will vote 17 times, once for each of the victims, on whether to recommend capital punishment.

For each death sentence, the jury must be unanimous or the sentence for that victim is life. The jurors are told that to vote for death, the prosecution's aggravating circumstances for that victim must, in their judgment, "outweigh" the defence's mitigators.

A juror can also vote for life out of mercy for Cruz.

During jury selection, the panellists said under oath that they are capable of voting for either sentence.