A pupil slit his teacher's throat as he was marking papers - because he had confiscated the boy's mobile phone.
The student had been caught playing with his phone by his teacher Sun Wakang during a chemistry lesson at a school in in Fuzhou, eastern China's Jiangxi province.
The following day, the pupil - referred to only as Lei in news reports - went to father-of-one Mr Sun's classroom and slit his throat from behind as he worked.
The 32-year-old died at the scene as the student fled. He has since turned himself in to police in Shanghai.
Mr Sun, who had worked as a chemistry teacher at Linchuan No. 2 Middle School for five years, had taken the student's mobile phone after the young boy had used it during a lesson, but it had been returned at the end of the day. Despite this, Lei attacked Mr Sun.