Police in Broward County, Florida, were responding on Wednesday to reports of an active shooter at a high school in the town of Parkland, a spokeswoman for the sheriff's office said.
Marjory Stoneman Douglas High School had been placed on a "code red" lockdown but had no information on victims, the spokeswoman said.
Local FOX-10 TV reported that five people were seen being treated by paramedics while other students were filing out of the school in a line. Parkland is about 15 miles (24 km) west of Fort Lauderdale.
This is a developing story.
