The US education secretary said schools have the “option” of arming teachers but refused to be drawn on whether she personally believed it was a good idea.

Speaking after 14 pupils and three staff members were killed in a Florida high school, Betsy DeVos said individual states and cities needed to decide for themselves whether teachers should be trained in the use of guns.

“I think this is an important issue for all states to grapple with and to tackle," she told conservative radio host Hugh Hewitt. "They clearly have the opportunity and the option to do that, and there are differences in how states approach this.

“I think this needs to be part of the broader, more robust conversation about how can we avoid these things in the future, and how can we ensure that when my child, your child, goes to school in the morning they’re going to go to a safe and nurturing environment, and they’re going to be able to pursue their learning in a way that is going to excite and energise them.”

Pressed further on whether she personally supported arming teachers if they were stringently vetted and rigorously trained, Ms DeVos she said: “I think that is a question and issue for communities to wrestle with, and I’ve seen approaches in different cities done different ways.

“It is one that has to happen at the local level and at the state level. Communities need to share best practices and results from the steps that they take to ensure that kids have a safe environment in which to learn.”

She added that she was “heartbroken” by Wednesday’s slaughter and that “there have been far too many of these situations”.

Nikolas Cruz has been charged with 17 counts of murder at the Marjory Stoneman Douglas High School in the city of Parkland.

Florida shooting – in pictures Show all 10 1 /10 Florida shooting – in pictures Florida shooting – in pictures Police arrest a suspect in connection with the shooting at the Marjory Stoneman Douglas High School in Parkland, Florida Reuters Florida shooting – in pictures Parents wait for news after reports of a shooting at Marjory Stoneman Douglas High School in Parkland, Florida AP Florida shooting – in pictures Anxious family members wait for news of students AP Photo/Wilfredo Lee Florida shooting – in pictures Students being evacuated from the school AP Florida shooting – in pictures Students being evacuated from the school Getty Florida shooting – in pictures People gather waiting for word from students AP Florida shooting – in pictures Parents waiting for news on their children AP Florida shooting – in pictures People gather at a hotel where students were taken after the shooting Getty Florida shooting – in pictures Florida Governor Rick Scott speaks to the media as he visits Marjory Stoneman Douglas High School following the shooting AFP/Getty Florida shooting – in pictures Dr. Igor Nichiporenko, Medical Director Trauma, left, and Dr. Evan Boyer, Medical Director, Emergency Services, speak about treating victims and the suspect at a press conference outside Broward Health North hospital AP

An arrest affidavit released by Broward County Sheriff’s Office stated that the 19-year-old former pupil, had "confessed" to the murders, after his arrest.

Ms DeVos told Mr Hewitt that Cruz had “put up lots and lots of signals and warning signs” ahead of the attack.

She said: “I think it’s critically important that we have a much more robust conversation around tracking and tackling mental health issues and really bringing this all together.