President Donald Trump ordered U.S. flags to be flown at half-staff Thursday to honor victims of the shooting at the Parkland, Florida, high school where 17 people were killed.

All public buildings and grounds should stay at half-staff until sunset on Feb. 19, Trump said in a presidential proclamation.

"Our Nation grieves with those who have lost loved ones in the shooting at the Marjory Stoneman Douglas High School in Parkland, Florida," said the proclamation.

The White House said Trump will address the nation about the Florida school shooting at 11 a.m. EST.