Gunfire erupted again at Parkland's Marjory Stoneman Douglas High School on Friday as part of a reenactment by ballistics experts of the 2018 massacre that left 14 students and three staff members dead.

The reenactment took place after a congressional delegation group toured the building, led by Democratic Congressman Jared Moskowitz and Republican Congressman Mario Diaz Balart, CBS Miami reported.

The reenactment is part of a lawsuit by the victims' families and the wounded that accuses the Broward County deputy assigned to the school of failing in his duty to protect the students.

Ballistics experts for the families conducted the test, firing up to 139 shots inside the three-story classroom building as part of the lawsuit against the families' primary targets: the school's then-assigned deputy, Scot Peterson, and his employer, the Broward Sheriff's Office, CBS News Miami reported.

Parents of the children killed during the mass shooting emphasized the importance of the reenactment to really understand the events that took place during the mass shooting in 2018, CBS News Miami.

Few have been inside the three-story building since the Valentine's Day 2018 shooting. The structure looms over the campus, locked behind a chain-link fence for use as evidence in last year's penalty trial for the shooter.

There is broken glass on the floor, along with wilted roses, deflated balloons and discarded gifts. Opened textbooks and laptop computers remain on students' desks, at least those that weren't toppled during the chaos.

In one classroom there is an unfinished chess game one of the slain students had been playing. The Associated Press was one of five media outlets allowed to tour the building after shooter Nikolas Cruz's jury went through.

The shooting, which sparked a nationwide movement for gun control, traumatized the South Florida community. Cruz, a 24-year-old former Stoneman Douglas student, pleaded guilty in 2021 and was sentenced to life in prison.

Not long after the lawmakers left the school, crews brought tables and ladders inside. Two helicopters hovered overhead. Cameras were placed outside and workers measured various distances from a mannequin head on top of a tripod and a door.

The simulation included the same types of weapons the gunman used. Originally it was said that blanks would be used. The judge said live ammunition will be used with a bullet safety device, CBS Miami reported. Former FBI agent Bruce Koenig, a ballistics expert for the families, testified that live rounds make a different sound than blanks.

Peterson, who worked for the Broward County Sheriff's Office and is named in the lawsuit, said he didn't hear all the shots and could not pinpoint their origin because of echoes. He got within feet of the building's door and drew his gun, but backed away and stood next to an adjoining building for 40 minutes, making radio calls. He has said he would have charged into the building if he had known the shooter's location.

Technicians outside the building were recording the sound of the gunfire, seeking to capture what deputy Peterson might have heard during the attack.

Families of the victims who filed the lawsuit contend Peterson knew Cruz's location, but retreated out of cowardice and in violation of his duty to protect their loved ones.

Peterson, 60, was found not guilty in June of felony child neglect and other criminal charges, the first U.S. trial of a law enforcement officer for conduct during an on-campus shooting.

The burden of proof is lower in the civil lawsuit. Circuit Judge Carol-Lisa Phillips allowed the reenactment, but made clear she was not ruling on whether the recording will be played at trial. That will have to be argued later, she said. It is likely Peterson's attorneys will oppose.

No trial date has been set. The families and wounded are seeking unspecified damages.