Duncan, Oklahoma schools get threats, go on alert after murder of Australian athlete OKLAHOMA CITY (Reuters) - Public schools in Duncan, Oklahoma, were on alert on Wednesday after police received threats against Duncan High School following the arrest of three teenagers in connection with the killing of a university student from Australia. The school, in a town of 24,000 about 80 miles south of Oklahoma City, was told of the anonymous threats on Tuesday night by police, schools superintendent Sherry Labyer said in a message on the Duncan Public Schools' website. The nature of the threats was not known. Christopher Lane, 23, of Melbourne, was killed by a gunshot in the back on Friday as he was jogging in Duncan. Duncan public schools were requiring students to stay on campus until a parent or guardian checked them out, Labyer said. She said children whose parents preferred to keep them home on Wednesday would be excused, Labyer said. A representative for Duncan High School declined to say if the suspects attended that school, and referred questions to police, who did not immediately return calls for comment. Chancey Allen Luna, 16, and James Francis Edwards Jr., 15, have been charged with first degree murder, according to the Stephens County District Attorney's office. Michael Dewayne Jones, 17, has been charged with use of a vehicle in the discharge of a weapon and accessory to murder after the fact, the District Attorney's office said. All three have been charged as adults, though Jones is considered a youthful offender. District Attorney Jason Hicks said he intended to pursue adult sentences for all three. In Jones' case that would be 5 years to 45 years for being an accessory after the fact, and 2 years to life for use of a vehicle in the discharge of a weapon. "I will be shocked if he is not found to be eligible to be sentenced as an adult," Hicks said of Jones. Terrell Cox, 16, a student at Duncan High School, told Reuters the three suspects were a "stand-off group that didn't seem to care that much." Cox said the atmosphere "pretty hectic" at his school on Wednesday. "People are either very scared or just not bothered," Cox said. This is not normal for Duncan ... It's like culture shock. Lane was jogging during a visit with his girlfriend and her family in Duncan when he was shot, police said. Under a 2005 U.S. Supreme Court ruling, they could not receive the death penalty because of their ages. The next court hearing for Jones has been scheduled for October 2, and a preliminary hearing for Edwards and Luna has been set for October 16. Reporting by Heide Brandes in Oklahoma City; Additional reporting by Mary Wisniewski; Editing by Andre Grenon