Security expert Joel Leffler was on a business trip in Dallas when he got a call from his son, a 16-year-old junior at Marjory Stoneman Douglas High School in South Florida, reports the Wall Street Journal.


"He called me as he was running out of the school," Mr Leffler said. "He was panicking, freaking out, he heard like eight gunshots, he was very scared.


His son said the shots seemed to be coming from the ninth-grade building, where his 14-year-old sister was. Leffler said he had to talk his son out of going to find his sister.


Leffler reached his daughter on the phone briefly. "She was whispering, hiding, then the phone went dead, because she didn't want anyone to hear her," he said. "And for the next 35 minutes before I heard from her, it was pretty terrifying."


When he finally heard from her, she told him her teacher had been shot and killed.


"She's 14 years old and she had to see multiple dead bodies,' he said. "It's something that you hear about all the time, and you never think it will happen to you."


Seventeen people were killed and more than a dozen injured when a gunman open fired at the high school Wednesday afternoon. Police said the suspect, a 19-year-old former student, is in custody.