The American flag above the White House is lowered to half staff following the shooting yesterday at Marjory Stoneman Douglas High School, February 15, 2018 in Washington, DC. Photo by Olivier Douliery/Abaca Press

The American flag above the White House is lowered to half staff following the shooting yesterday at Marjory Stoneman Douglas High School, February 15, 2018 in Washington, DC. Photo by Olivier Douliery/Abaca Press

The American flag above the White House is lowered to half staff following the shooting yesterday at Marjory Stoneman Douglas High School, February 15, 2018 in Washington, DC. Photo by Olivier Douliery/Abaca Press

The American flag above the White House is lowered to half staff following the shooting yesterday at Marjory Stoneman Douglas High School, February 15, 2018 in Washington, DC. Photo by Olivier Douliery/Abaca Press

WASHINGTON, USA - FEBRUARY 15: President Donald Trump addresses the nation after the mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida, in Washington, USA on February 15, 2018. Former student Nikolas Cruz has been apprehended and charged with 17 counts of premeditated murder after attacking his former school with an AR-15 style assault rifle. Samuel Corum / Anadolu Agency

WASHINGTON, USA - FEBRUARY 15: President Donald Trump addresses the nation after the mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida, in Washington, USA on February 15, 2018. Former student Nikolas Cruz has been apprehended and charged with 17 counts of premeditated murder after attacking his former school with an AR-15 style assault rifle. Samuel Corum / Anadolu Agency

WASHINGTON, USA - FEBRUARY 15: President Donald Trump addresses the nation after the mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida, in Washington, USA on February 15, 2018. Former student Nikolas Cruz has been apprehended and charged with 17 counts of premeditated murder after attacking his former school with an AR-15 style assault rifle. Samuel Corum / Anadolu Agency

WASHINGTON, USA - FEBRUARY 15: President Donald Trump addresses the nation after the mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida, in Washington, USA on February 15, 2018. Former student Nikolas Cruz has been apprehended and charged with 17 counts of premeditated murder after attacking his former school with an AR-15 style assault rifle. Samuel Corum / Anadolu Agency

WASHINGTON, USA - FEBRUARY 15: President Donald Trump addresses the nation after the mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida, in Washington, USA on February 15, 2018. Former student Nikolas Cruz has been apprehended and charged with 17 counts of premeditated murder after attacking his former school with an AR-15 style assault rifle. Samuel Corum / Anadolu Agency

President Donald Trump delivers a statement on the South Florida school shooting from the Diplomat room of the White House, February 15, 2018 in Washington, DC. Photo by Olivier Douliery/Abaca Press

President Donald Trump delivers a statement on the South Florida school shooting from the Diplomat room of the White House, February 15, 2018 in Washington, DC. Photo by Olivier Douliery/Abaca Press

President Donald Trump delivers a statement on the South Florida school shooting from the Diplomat room of the White House, February 15, 2018 in Washington, DC. Photo by Olivier Douliery/Abaca Press

President Donald Trump delivers a statement on the South Florida school shooting from the Diplomat room of the White House, February 15, 2018 in Washington, DC. Photo by Olivier Douliery/Abaca Press

President Donald Trump delivers a statement on the South Florida school shooting from the Diplomat room of the White House, February 15, 2018 in Washington, DC. Photo by Olivier Douliery/Abaca Press

President Donald Trump delivers a statement on the South Florida school shooting from the Diplomat room of the White House, February 15, 2018 in Washington, DC. Photo by Olivier Douliery/Abaca Press

President Donald Trump delivers a statement on the South Florida school shooting from the Diplomat room of the White House, February 15, 2018 in Washington, DC. Photo by Olivier Douliery/Abaca Press

President Donald Trump delivers a statement on the South Florida school shooting from the Diplomat room of the White House, February 15, 2018 in Washington, DC. Photo by Olivier Douliery/Abaca Press

President Donald Trump delivers a statement on the South Florida school shooting from the Diplomat room of the White House, February 15, 2018 in Washington, DC. Photo by Olivier Douliery/Abaca Press

WASHINGTON, USA - FEBRUARY 15: President Donald Trump addresses the nation after the mass shooting at Marjory Stoneman Douglas High School in Parkland, Florida, in Washington, USA on February 15, 2018. Former student Nikolas Cruz has been apprehended and charged with 17 counts of premeditated murder after attacking his former school with an AR-15 style assault rifle. Samuel Corum / Anadolu Agency