Dyfed-Powys Police is dealing with an incident at Amman Valley School in Carmarthenshire.
Three people have been injured and are receiving treatment.
One person has been arrested and we are not looking for anyone else in connection with this incident.
Emergency services remain at scene and the school has been closed while investigations continue.
We are working closely with the school and Carmarthenshire County Council.
We are aware that there is footage of the incident currently circulating on social media. We would ask that this is removed to avoid contempt of court and distress to those affected.
We would ask the people do not speculate while there is a police investigation ongoing.
A Welsh Ambulance Service spokesperson said: “We were called shortly after 11.15am to an incident on Margaret Street in Ammanford.
“We sent four emergency ambulances and the hazardous area response team to the scene, where crews were supported by two Cymru high acuity response unit paramedics and an operational manager.
“Advanced critical care support was delivered by the Emergency Medical Retrieval and Transfer Service in two Wales Air Ambulance charity helicopters.”
