An active shooter situation is underway at a high school in Parkland Florida, where at least three students are dead and over fifty are injured.

Daily Mail reported that a “heavily armed” gunman entered Majory Stoneman Douglas High School and began shooting with a “long” gun at just after 2pm. Police have surrounded the school and have said this remains an active shooter situation, although there are reports that a student was seen fighting with the gunman in a classroom.

Many students have barricaded themselves inside their classrooms, while others were seen running out of the building with their book bags as police and SWAT teams swarmed the school. Some reports indicate the shooter has fled the school, blending in with other students who were running from the building. The shooter was seen to be wearing a burgundy shirt and black pants.

“The president has been made aware of the school shooting in Florida. We are monitoring the situation. Our thoughts and prayers are with those affected,” said White House deputy press secretary Lindsay Walters.

“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,” Trump wrote on Twitter. “Just spoke to Governor Rick Scott. We are working closely with law enforcement on the terrible Florida school shooting.”

One mother whose daughter is still barricaded inside a classroom said she received a text from the girl saying, “There’s been a shooting in school … and it’s for real.”

“She was texting me up until about four minutes ago and now she’s not responding and I’m getting nervous. Last she texted me she was in a building from across where the shooting was at. I’m on pins and needles because she isn’t responding to me now,” the mother told reporters from outside the police parameter.

We will update you further as this story develops.