A former student at a Florida high school has opened fire in the school, causing 17 deaths and wounding at least 14 people before he was arrested.
The attack at Marjory Stoneman Douglas High School in Parkland, about 72 kilometres north of Miami, sent hundreds of panicked students fleeing into the streets while dozens of police and emergency services personnel swarmed the area.
"There are numerous fatalities. It's a horrific situation," Broward Country Schools Superintendent Robert Runcie said.
CNN has reported that 17 people are dead.
The gunman, about 18 years old, surrendered to police quietly, said Broward County Sheriff Scott Israel.
"It's catastrophic," he said. "There really are no words."
Fourteen wounded people were transported to area hospitals, Israel told a press conference said.
He added that police in tactical gear were still searching the school for victims.
The Associated Press has identified the alleged shooter as Nicolas Cruz, but Israel offered few details on his motive.
"There was a time when he did attend the school," Israel said. "I don't know why he left, I don't know when he left."
It was the 18th shooting in a US school so far this year, according to gun control group Everytown for Gun Safety.