Assistant Principal Denise Reese waves to teachers as they pull into the parking lot at Marjory Stoneman Douglas High School on Friday, Feb. 23, 2018 in Parkland, Fla. Teachers and administrators returned for the first time since the Valentine's Day shooting that killed several people. (Mike Stocker/South Florida Sun-Sentinel via AP)
Assistant Principal Denise Reese waves to teachers as they pull into the parking lot at Marjory Stoneman Douglas High School on Friday, Feb. 23, 2018 in Parkland, Fla. Teachers and administrators returned for the first time since the Valentine's Day shooting that killed several people. (Mike Stocker/South Florida Sun-Sentinel via AP)
Ariana Gonzalez is over come with emotion as she visits a cross setup for her friend, football coach Aaron Feis, at the memorial in front of Marjory Stoneman Douglas High School as teachers and staff are allowed to return to the school for the first time since the mass shooting on campus on February 23, 2018 in Parkland, Florida. Police arrested 19-year-old former student Nikolas Cruz for killing 17 people at the high school. (Photo by Joe Raedle/Getty Images)
Ariana Gonzalez is over come with emotion as she visits a cross setup for her friend, football coach Aaron Feis, at the memorial in front of Marjory Stoneman Douglas High School as teachers and staff are allowed to return to the school for the first time since the mass shooting on campus on February 23, 2018 in Parkland, Florida. Police arrested 19-year-old former student Nikolas Cruz for killing 17 people at the high school. (Photo by Joe Raedle/Getty Images)
A sign is seen on the fence around Marjory Stoneman Douglas High School in front of the freshman dorm where a mass shooting took place on campus on February 23, 2018 in Parkland, Florida. Police arrested 19-year-old former student Nikolas Cruz for killing 17 people at the high school. (Photo by Joe Raedle/Getty Images)
A sign is seen on the fence around Marjory Stoneman Douglas High School in front of the freshman dorm where a mass shooting took place on campus on February 23, 2018 in Parkland, Florida. Police arrested 19-year-old former student Nikolas Cruz for killing 17 people at the high school. (Photo by Joe Raedle/Getty Images)
Marjory Stoneman Douglas student Madisyn Menthaca, 15, places roses on the memorials on a hillside with her mother, Kelly Savino, where 17 students and teachers were killed at Marjory Stoneman Douglas High School in the second-deadliest shooting at a U.S. public school. Jonathan Newton/The Washington Post
Marjory Stoneman Douglas student Madisyn Menthaca, 15, places roses on the memorials on a hillside with her mother, Kelly Savino, where 17 students and teachers were killed at Marjory Stoneman Douglas High School in the second-deadliest shooting at a U.S. public school. Jonathan Newton/The Washington Post
Assistant Principle Denise Reed (L) hugs a school employee as she arrives at Marjory Stoneman Douglas High School as teachers and staff are allowed to return to the school for the first time since the mass shooting on campus on February 23, 2018 in Parkland, Florida. Police arrested 19-year-old former student Nikolas Cruz for killing 17 people at the high school. (Photo by Joe Raedle/Getty Images)
Assistant Principle Denise Reed (L) hugs a school employee as she arrives at Marjory Stoneman Douglas High School as teachers and staff are allowed to return to the school for the first time since the mass shooting on campus on February 23, 2018 in Parkland, Florida. Police arrested 19-year-old former student Nikolas Cruz for killing 17 people at the high school. (Photo by Joe Raedle/Getty Images)
Broward Schools Superintendent Robert Runcie waves after meeting with the media in front of Marjory Stoneman Douglas High School as teachers and staff are allowed to return to the school for the first time since the mass shooting on campus on February 23, 2018 in Parkland, Florida. Police arrested 19-year-old former student Nikolas Cruz for killing 17 people at the high school. (Photo by Joe Raedle/Getty Images)
Broward Schools Superintendent Robert Runcie waves after meeting with the media in front of Marjory Stoneman Douglas High School as teachers and staff are allowed to return to the school for the first time since the mass shooting on campus on February 23, 2018 in Parkland, Florida. Police arrested 19-year-old former student Nikolas Cruz for killing 17 people at the high school. (Photo by Joe Raedle/Getty Images)
School bus driver Pearlie Corker (L) is hugged by Dr. Rosalind Osgood, a school board member, as they visit Marjory Stoneman Douglas High School as teachers and staff are allowed to return to the school for the first time since the mass shooting on campus on February 23, 2018 in Parkland, Florida. Ms. Corker was ready to pick up students from the high school as the shooting started. Police arrested 19-year-old former student Nikolas Cruz for killing 17 people at the high school. (Photo by Joe Raedle/Getty Images)
School bus driver Pearlie Corker (L) is hugged by Dr. Rosalind Osgood, a school board member, as they visit Marjory Stoneman Douglas High School as teachers and staff are allowed to return to the school for the first time since the mass shooting on campus on February 23, 2018 in Parkland, Florida. Ms. Corker was ready to pick up students from the high school as the shooting started. Police arrested 19-year-old former student Nikolas Cruz for killing 17 people at the high school. (Photo by Joe Raedle/Getty Images)