Two teenage girls have been arrested on suspicion of planning to murder a teacher.
Gwent Police said the girls, 14 and 15, were arrested at Cwmcarn High School in south Wales on Thursday because of concerns about their behaviour.
Detectives said they were notified about the alleged plot by a teacher at the school.
A force spokesman stressed "no physical confrontation" had taken place.
The 15-year-old girl was arrested on suspicion of threats to kill, possession of a "bladed article" on school premises and conspiracy to commit murder.
It is believed a kitchen knife had been found in the girl's school bag.
Her 14-year-old friend was arrested on suspicion of conspiracy to commit murder.
More top news
President Obama said he was "mortified" after a man walked up to him at a polling station and warned him not to touch his girlfriend.
Teenagers are being tricked into sending inappropriate photographs through social media, police say.
June and Barry Steenkamp tell Good Morning Britain they accept the judge's decision but still do not believe Pistorius' version of events.