Former student opens fire at Florida high school, killing 17

Students released from a lockdown embrace following a shooting at Marjory Stoneman Douglas High School on Wednesday. (John McCall/South Florida Sun-Sentinel via AP)

Medical personnel tend to a victim following a shooting at Marjory Stoneman Douglas High School in Parkland, Fla. Wednesday. (John McCall/South Florida Sun-Sentinel via AP)

PARKLAND, Fla. — A former student opened fire with a semiautomatic rifle at a Florida high school Wednesday, killing at least 17 people and sending scores of students fleeing into the streets in the nation’s deadliest school shooting since a gunman attacked an elementary school in Newtown, Connecticut.