AKIPRESS.COM - At least 17 people are dead after a 19-year-old man opened fire at a high school campus 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, media reports say.

As the attack unfolded students were forced to hide as police swooped in on the building.

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

Broward County Sheriff Scott Israel told reporters Cruz killed three people outside the school, before entering the building and killing another 12, BBC reported.

Two people later died after being taken to hospital. "It's catastrophic. There really are no words," Sheriff Israel tweeted later.

Dr Evan Boyar of Broward Health told reporters that 17 people total had been taken to area hospitals.

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

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