The gunman who allegedly opened fire on a large Florida high school, killing 17 people and causing 3000 students to flee in panic, is a former student with an apparent gun obsession.

The 19-year-old student, Nikolas Cruz, was expelled from Marjory Stoneman Douglas High School recently for disciplinary reasons, Broward County Sheriff Scott Israel said.

Authorities are not sure if he had enrolled in another school.

He allegedly started shooting outside the high school just before the end of the school day on Wednesday. He continued shooting as he entered the school, leaving bodies scattered in the hallways and out the front of the school grounds.