A juvenile is under arrest for threatening a mass shooting at Marjory Stoneman Douglas High School. An anonymous call coming into the Broward County Sheriff's regional communications office around 11 last night tipping investigators off to this threat spotted on a social media site. Sheriff's spokeswoman Claudinne Caro says the threat management unit analyzed the data and detectives were able to nab the suspect. The teen is being charged with one count of writing threats to conduct a mass shooting. The threat comes two days after a deadly shooting at a high school in Michigan and nearly four years after the Parkland massacre.