Two teenagers who survived America's deadliest high school shooting have committed suicide in the last week, bringing fresh tragedy to the Florida community.

A 17-year-old boy who attended the Marjory Stoneman Douglas High School in Parkland, Florida - where 17 people were killed last year - died on Saturday in what police are treating as a suicide.

The boy, who has not been named, was in his second year of high school and reportedly died from a gun shot wound to the head.

It comes just days after Sydney Aiello, a 19-year-old recent graduate of the school, took her own life. Ms Aiello's family said the teenager had been diagnosed with post-traumatic stress disorder and suffered from survivor’s guilt after the shooting, in which one of her best friends, Meadow Pollack, was shot dead.

Former student Nikolas Cruz entered the high school armed with a semi-automatic rifle on February 14, 2018 and left 14 students and three staff members dead, with 17 others wounded.