It's every parent's worst nightmare, and for Joel Leffler it came in the form of a phone call from his son Wednesday afternoon.
"You could tell he was panicking and running. He said there had been about eight shots," Leffler said.
Leffler's 16-year-old son, Bryce, is a sophomore at Marjory Stoneman Douglas High School in Parkland, Florida, and his 14-year-old daughter, Cloe, is a freshman.
In the moments after the call from his son, Leffler says he was able to get his daughter on the phone.
"She was talking to me, she was whispering and then the phone went dead," Leffler said.
More than 30 agonizing minutes would pass before Leffler would again hear from his daughter, who by then had been rescued from the school by SWAT officers.
Leffler says he's thankful his two children are safe, and his thoughts are with parents whose children have yet to be accounted for.
"Fortunately my daughter is safe, but there are other families out there that are not," Leffler said.
Broward County, Florida, sheriff's officials say 17 people have died following the shooting at the school.