A 17-year-old boy has been arrested on suspicion of attempted murder after three people were injured at a secondary school which went into lockdown.
Children described to their parents how they were lying on the floor and hiding under the tables during the incident at The Birley Academy in Sheffield on Wednesday morning.
A child was assaulted and two adults suffered minor injuries in the incident, one of these from a “sharp object which is believed to be broken glass”, police said.
Officers said all three victims were checked-over by paramedics at the scene, with nobody going to hospital, and the child involved “thankfully, has no visible injuries”.
Dozens of parents arrived at the school on Wednesday morning to collect their children, with many responding to frantic texts from students in the school following the lockdown.
One parent told BBC Radio Sheffield how their child texted saying: “Mum, there’s a lockdown at school.
“There as an alarm, right bad, and then the head teacher told us to go back inside.
“The head teacher came out and told us to go back inside and now we’re on the floor. I don’t want to be here right now.”
Another parent said: “There’s a lot of rumours flying about.
“Kids were texting, saying there were people still in the building. (My daughter) texted saying she was under a table crying so I shot straight round.
“It wasn’t nice. I was a bit overwhelmed, so I nearly climbed over the gates at one point. But I spoke to the police and they assured me that everything was OK.”
There was a visible police presence at the school on Wednesday after officers first responded to the site on Birley Lane at around 8.50am.
Speaking at a press conference outside the school, South Yorkshire Police Assistant Chief Constable Dan Thorpe said his officers arrested a 17-year-old boy at The Birley Academy “within minutes of the initial call”.
This was on suspicion of attempted murder and the teenager remains in custody, he said.
Mr Thorpe said: “The three victims of this incident – two adults and a child – suffered minor injuries and were checked over at the scene by colleagues from the Yorkshire Ambulance Service.
“The two adults both suffered minor injuries – one from a sharp object, which is believed to be broken glass. The child was assaulted and, thankfully, has no visible injuries.
Mr Thorpe praised the school staff for their actions following the “frightening ordeal”, saying they “helped keep the school community safe”.
He said: “Birley is a close-knit community and, while this event concluded in a swift arrest, it will no doubt cause ongoing concern”.
Mr Thorpe said officers will continue to patrol the area in the coming days and be available for the community.
The senior officer also appealed to everyone not to post images on social media which may harm the police investigation.
School head Victoria Hall told reporters outside the school: “I just wanted to thank all of our students and staff who helped manage the situation this morning, and our staff who prioritised the safety and wellbeing of all of our students.”
Mrs Hall also praised the students’ “exemplary behaviour”, saying the school will be open on Thursday morning as usual.
The incident in Sheffield follows another in Ysgol Dyffryn Aman, also known as Amman Valley School, in Ammanford, Carmarthenshire, last week.
A 13-year-old girl has appeared in court charged with three counts of attempted murder after two teachers and a student were attacked.