Christopher Beamon, a pupil at Ponder High School, Denton County, Texas, wrote an imaginative account of an attack on his classmates that was so vivid that it put him into custody in a juvenile detention centre.

Asked to write an essay about coming home in the dark and hearing a noise, Christopher described a violent gun attack on his fellow pupils, with the story later being read to the class.

Schools across the United States are worried about the threat of violence, after attacks such as at Columbine High School

But in a process described by the boy's family's lawyer as "confused, absurd and then bizarre", the school called in the police after parents had complained about the threatening tone of the essay.

The local school district superintendent, Byron Welch, says that because "elements of a criminal act may have taken place" they were obliged to inform the police, who then took the decision to detain the schoolboy.

Defending the school's response, Dr Welch said: "It was the student's choice to use real people in a violent setting.

"When we receive a report that someone feels that they have been threatened by the written or spoken words of a student, we have to respond."

The schoolboy was taken into custody last Thursday and after the district attorney declined to prosecute, he was released on Tuesday.

The essay sparked concern at a time when schools in the United States are highly-sensitive to the threat of violence, following a series of school shootings including the gun attack at Columbine High School in Colorado.