A 14-year-old girl who fatally stabbed her 16-year-old sister in the back has been detained for three-and-a-half years for manslaughter.
The girl was cleared by a jury of the murder of her sister but had earlier admitted the manslaughter charge.
Bradford Crown Court had heard the pair started fighting after an argument about the 16-year-old's boyfriend.
A judge told the girl she "did a terrible thing" by attacking her with a carving knife "to deadly effect".
'I love her'
Mr Justice McKinnon said: "The knife entered the deceased's body at the back just to the side of the left shoulder blade at a depth of 12cm, puncturing the lung and causing severe internal bleeding.
"As a result of remarks you made at the time about the deceased's boyfriend, the deceased attacked you, grabbing your hair and pulling it hard."
The 14-year-old then went into the kitchen, grabbing the nearest knife and returned to the living room, where she stabbed her sister.
The jury took less than five-and-a-half hours to find the girl not guilty of murder but guilty of manslaughter by way of provocation.
During the trial the girl had said she "just wanted to scare" her sister but she was "proper angry and upset".
She told the court: "I'm sorry and I love her and I want her back."
Outside court, Det Supt Andy Brennan of West Yorkshire Police, read a statement on behalf of the mother and family.
It said: "We all miss my daughter's enormous big smile and the laughter that we shared.
"We got her GCSE results this summer and she had got really good grades, all As and Bs, and we are very proud of her.
"Although my heart is broken for the loss of my beautiful daughter, I feel my youngest daughter should be at home with her family around to help grieve the deep loss she feels for her sister, and also be left in peace to help her try to rebuild her life.
"We feel she will live with this for the rest of her life and I think that is punishment enough as that is like a life sentence in itself."