The Oklahoma high school where the three boys accused of the drive-by murder of Australian baseballer Chris Lane attended has added extra security after "anonymous threats".
Duncan High School superintendent Sherry Labyer, in a message posted on the school's website, told parents "if you believe that you prefer to keep your child or children home tomorrow, we respect your decision".
"We were informed by the Duncan Police Department of anonymous threats involving Duncan High School," Dr Labyer wrote.
"The credibility of the person or persons communicating the threats is very difficult to ascertain.
"However, we want to be proactive in taking reasonable precautions."
James Edwards, 15, Chancey Luna, 16, and Michael Jones, 17 were arrested on Friday, just hours after the shooting, for what police and prosecutors have described as a random drive-by murder of Mr Lane, who was jogging along a Duncan road.
Edwards and Luna have been charged with first degree murder, while Jones is charged with being an accessory.
Police allege one of the boys said they shot Mr Lane, 22, for "the fun of it" and because they were "bored".
Edwards and Luna have been refused bail, while Jones' bail has been set at $US1 million ($A1.11 million).
"Last Friday's shooting death here in Duncan is a tragedy in so many respects," Dr Labyer wrote.
"As a School District, our hearts and prayers are certainly with the family and friends of Christopher Lane.
"Since the shooting, our administrators have been in continuous contact with the Duncan Police Department to ensure that we are aware of any information that may affect the safety of our students."
