The mother of a teenage boy who stabbed a girl in a masked attack at a school said she received a message from her son saying "sorry" shortly after the attack, a trial has heard.
Police were called to Thorpe St Andrew School, near Norwich, on 11 March following reports a 15-year-old had been stabbed in the back.
The defendant, who is 16 and cannot be named for legal reasons, denies attempted murder, but has admitted possessing a kitchen knife without lawful authority and wounding with intent.
After learning about the unfolding events on social media, his mother told the jury at King's Lynn Crown Court she "was in complete shock" when she realised her son was involved.
The mother told the trial that her son was "very quiet, very funny, very smart" and had a "dry sense of humour".
The court has previously heard how the defendant had written notes saying he hated women while the schoolgirl victim described to police how she told a teacher "Sir, I've been stabbed".
During Monday's proceedings, the mother described the night before the attack as "completely normal", and said her son left for school at his usual time the following morning.
She said she first became aware something was happening when she was "doom-scrolling".
She messaged her son asking if he was OK, but said she did not "get an immediate response".
"When you realise there has been an incident at the school and you don't hear from children, it's worrying," she said.