This is a developing story There is news of casualties following a high school shooting in Florida, reports the BBC and several other outlets this evening. Local media currently in the Parklands area also confirms that police have responded to reports of 'an active shooter' at the Majory Stoneman Douglas High School. https://twitter.com/piersmorgan/status/963871333254823937 Witnesses say that 'several people' are being treated for injuries outside the school. The shooter - who used a 'long gun' - remained at large at 8.30pm Irish time on Wednesday. https://twitter.com/kpass2016/status/963873941226897409 Aerial footage from CNN affiliate WSVN shows a number of injured people lying on the ground outside the school. "Dozens of police vehicles are on site, including one tank, along with a team of heavily armed law enforcement officers," CNN adds. And one student told WSVN that when he first heard the shots, he thought it was Valentine's Day balloons popping. https://twitter.com/BrianEntin/status/963871055831076867 DailyMail.com states that the gunman was wearing a gas mask and has shot "at least 20" at the school. The website goes on to say that students had to barricade themselves into their classrooms. President Trump "has been made aware" of the situation, Deputy Press Secretary Lindsay Walters revealed. "We are monitoring the situation. Our thoughts and prayers are with those affected," she added.