An American school safety adviser says there is no quick fix to school shootings.

This from an American school safety adviser after one of the deadliest school shootings in US history.

17 people were killed yesterday when an ex-student opened fire at a Florida high school.

Dr Amy Clinger told Mike Hosking we can't say another school shooting won't happen, because it will.

"Every person in a school building from the principal to the custodian to the student needs to have adequate training in preventing, in responding, in identifying."

She says schools should always be monitoring at-risk students who could become shooters.

"We need to out a heavier emphasis on prevention and being proactive rather than waiting until the bullets start flying to figure out what we're going to do."

READ MORE: Ex-student charged with Florida school deaths

The case has lead to renewed calls for better gun control, with the students caught up in the shooting leading the way.

Staff and board members have been counselling the school's students, and superintendent Rob Runcie says the message from students is overwhelming.

"Students have been saying that now is the time for this country to have a real conversation on sensible gun control laws."

Runcie says he hopes America can get in done in this generation, "but if we don't, they will".

Meanwhile, US President Donald Trump said at a press conference the Florida shooting shouldn't have been able to happen in modern day America.

He says better mental healthcare is needed to ensure it never happens again.

"No child, no teacher should ever be in danger in an American school. No parent should ever have to fear for their sons and daughters when they kiss them goodbye in the morning."

There have been 291 school shootings in the US in the past five years, and there have already been 18 shootings this year.