No less than 17 individuals are dead following a 19-year-old man opened fire at a secondary school grounds in Parkland, Florida, police have said.

The suspect has been named as Nikolas Cruz, 19, and is a former student at the school who had been expelled.

As the assault unfurled, students were compelled to stow away as police swooped in on the building.

It is one of the deadliest school shootings since 26 individuals were slaughtered at a Connecticut school in 2012.

Broward County Sheriff Scott Israel told columnists Cruz murdered three individuals outside the school, before entering the building and slaughtering another 12.

Two individuals later passed on in the wake of being taken to the hospital.

“It’s catastrophic. There really are no words,” Sheriff Israel tweeted later.

Dr. Evan Boyar of Broward Health told correspondents late on Wednesday that 17 individuals altogether had been taken to area hospitals.

He included that Mr. Cruz was among those treated and was discharged into police custody. Three individuals remained in a critical condition and three others were in stable condition, he said.

The victims are as yet being distinguished. Sheriff Israel said a football coach was among the dead but no names have been released yet.