FORT LAUDERDALE, FL- The sentencing phase in the trial of confessed killer Nikolas Cruz got underway in a Broward courtroom on Monday.

In the first of what is expected to be many days of emotional testimony, a student and teacher from Marjory Stoneman Douglas High School took the stand and recounted the terror that unfolded on Valentine’s Day in 2018.

Danielle Gilbert, a junior at the time, cried as cell phone video she recorded on the day of the attack was played for the jury.

Multiple gunshots could be heard in the background.

Nikolas Cruz, seated at a table with his attorneys, put his head down while the video was shown.

“We were sitting like sitting ducks,” Gilbert said.

Teacher Brittney Sinitch was working on a project with her class when she heard the shots.

“We were having so much fun until I heard what I described as the loudest noise you could possibly imagine,” Sinitch said on the stand.

She then called 911.

In his opening statement, Assistant State Attorney Michael Satz recounted Cruz’ actions that day calling it “a planned, systematic mass murder of 14 children, an athletic director, a teacher and a coach.”

In a video made by Cruz shortly before the shooting he stated his intentions to kill “at least 20 people with an AR-15 [rifle.]”

The jury will decide if Cruz will get life in prison or the death penalty.

A unanimous jury decision is required for a death sentence.

Testimony resumes on Tuesday.