Updated at 4: 15 p.m. ET
The Broward County Sheriff's Office says a suspect is in custody in the shootings at Marjory Stoneman Douglas High School in the city of Parkland, Fla. Parkland is northwest of Fort Lauderdale.
The school was locked down as some students were escorted outside while others were being advised to remain barricaded inside.
Broward County Public Schools and the sheriff's office report "possible multiple injuries."
Authorities have not determined a motive for the shooting.
Florida Gov. Rick Scott as well as President Trump have been told about the shooting.
This is a developing story. Some things that get reported by the media will later turn out to be wrong. We will focus on reports from police officials and other authorities, credible news outlets and reporters who are at the scene. We will update as the situation develops.