A father says his 15-year-old son was walking between classes at Desert Oasis High School one morning in January 2014, listening to music in his headphones, when an older classmate attacked him from behind and sent him to the hospital with a broken nose, a concussion and a head wound that required seven staples.

Now James Hensley, the boy’s father, is pursuing a lawsuit that accuses the Clark County School District and Desert Oasis employees of discounting the boy’s injuries and covering up violence at the school to avoid scrutiny from central administrators.

According to the lawsuit, which was filed in Clark County District Court in January and removed to federal court April 26, Stratton Hensley was “viciously battered by another student” who is two years older. The other student ran up behind the 145-pound boy and punched him several times in the back of the head and face, slamming his head into a locker and causing an open wound above his ear, the complaint alleges.

“It wasn’t a fight,” the boy’s attorney, Cal Potter III, said Wednesday. “He was attacked, and there was nobody around to stop it.”

The lawsuit lists the school district and several Desert Oasis employees — including the school’s principal, dean and a teacher — as defendants in the case, claiming that each of them created a dangerous situation for Stratton and were “deliberately indifferent” to his safety.

In the lawsuit, Hensley claims the school’s “first aid and safety assistant” at the time wrote in a required-parent-conference report that Stratton suffered no injuries.

The school neglected to call Hensley, who instead heard about the attack in a text message from his son, the father said Wednesday.

“My son was just pummeled,” Hensley said. “They didn’t even call us. … They asked him if he could walk home.”

Hensley said he helped his son walk to the car and took him to an urgent-care facility. A doctor there said Stratton had a broken nose and sent the teenager to a nose specialist, who told him he needed emergency surgery the next day.

Stratton, now 17, has lost faith in authority since the attack, his father said. Hensley pulled his son out of Desert Oasis and enrolled him in online courses at Odyssey Charter School. The teenager is expected to graduate in May, Hensley said.

According to the complaint, the school chose not to pursue a felony battery charge against the boy’s attacker to avoid being designated a “turnaround school.”

Schools become eligible for placement in the district’s turnaround zone after student performance has slipped for several years. The district tracks graduation rates, student test scores, credit sufficiency and other data to identify potential turnaround schools.

A turnaround campus typically receives a new principal with flexibility over hiring and firing decisions and more resources to offer incentive pay to recruit more experienced educators to the school.

The school district filed a motion to dismiss Hensley’s lawsuit on Tuesday, arguing that “the complaint is barren of factual allegations.”

“Whether a school is a ‘turnaround’ school has no connection to a student fight and what may, or may not have been documented” after the fight, the motion claims.

According to the document, Stratton’s “alleged injuries” were caused by a private individual and not the school’s employees, and no employees were present when the attack happened or caused the boy to be struck by another student.

“The district believes the allegations in the lawsuit against it and our district employees are without support and will be vigorously defending against the claims,” district spokeswoman Michelle Booth said Wednesday.