Writing on Twitter he said: “My prayers and condolences to the families of the victims of the terrible Florida shooting. No child, teacher or anyone else should ever feel unsafe in an American school.
“Just spoke to Governor Rick Scott. We are working closely with law enforcement on the terrible Florida school shooting.”
His tweets come after The Broward Sheriff’s Office confirmed the shooter had been taken into custody.
Coral Springs Mayor Skip Campbell confirmed there were “multiple fatalities.”
Police surrounded Marjory Stoneman Douglas High School in Parkland, Broward County, and a SWAT team swarmed the building to try to bring the situation under control.
The gunman, believed to be wearing a gasmask, opened fire shortly after 2pm local time (7pm GMT).
The school was placed on a “code red” lockdown and students reportedly barricaded themselves in classrooms while others have been seen fleeing the scene.
SWAT teams are currently on the scene along with the FBI, with some students believed to still be locked in their classrooms.
A person of interest is believed to be a student who was in class earlier that day.
Local Senator Marco Rubio are currently monitoring the situation.
In a statement he said: “We are monitoring the horrible unfolding situation in Broward County, Florida with reports of a shooting at a local high school.
Student Michael Katz told ABC News that at the end of the day he “heard what sounded like a garbage truck like banging.”
“Then also I hear, ‘Boom, boom, boom.’ I hear screaming everywhere,” he said. “I just got underneath my teacher’s desk.
“We had police invade the school, and we were taken out. “Fortunately, my father was there to pick me up.”
This is the 18th school shooting in the US this year.