As gun shots rang out at a Florida high school on Wednesday, a call on the school's security radio asked if the loud sounds were firecrackers.

Aaron Feis, in his capacity as a school security guard, responded: "No, that is not firecrackers." It was the last anyone heard from him.

It later emerged that as others fled the gunman, Mr Feis had put himself in harm's way, using his own body to shield his students.

"He died the same way he lived - he put himself second," said Denise Lehtio, a spokeswoman for Marjory Stoneman Douglas High School in Parkland, Florida.

"He was a very kind soul, a very nice man. He died a hero."

Mr Feis, who a former student of Marjory Stoneman himself, was also an assistant football coach at the school.