Detectives were given more time on Friday to question a teacher at a school in Nottinghamshire who is being held on suspicion of attempting to murder a teenage pupil and assaulting two other children.
Jack Waterhouse, 14, was taken to hospital with serious head injuries after an incident in a classroom at All Saints' Roman Catholic School in Mansfield on Wednesday morning. He is now in a serious but stable condition in hospital.
Peter Harvey, a 49-year-old teacher from the school, is being questioned by detectives on suspicion of attempted murder and two counts of assault on other children at the same time, police said.
Detectives said he had reportedly used a weapon during the alleged assault. Officers have been given permission by magistrates to hold him until Friday evening.
"Mr Harvey remains in custody. Inquiries are ongoing. He has not yet been charged," a Nottinghamshire police spokesman said.
Media reports said former pupils and parents had expressed surprise that the science teacher was the one suspected of being involved.
"I didn't think the pupils would give him stick," ex-pupil Tom Blythe, 19, was quoted as saying. "He was actually a decent bloke and got involved in school plays."
Detective Superintendent Adrian Pearson said other pupils in class at the time were assisting the investigation and that the incident had been out of character for the school.
"It's a school where people send their children from a wide catchment area. There have been no similar incidents before," he said.
On its website, the school said it had been a Performing Arts College since 2002 and had been described as "rapidly improving" in a 2009 Ofsted inspection.
"All Saints' School is a lively, Catholic comprehensive school with a very special, warm ethos which is recognised by all who visit," the headteacher said on the website.