The Gwinnett County school district initially said it was investigating a group of baseball players in 2015 for “misbehavior” and “inappropriate physical contact.”

What it didn’t reveal was that a younger teammate had reported being sexually assaulted.

Even after the players were disciplined for sexual battery, the district cited student confidentiality to withhold details from the public and described the incident as hazing.

Across the U.S., perhaps nowhere is student-on-student sexual assault as dismissed or as camouflaged as in boys’ sports, an Associated Press investigation found. Mischaracterized as hazing and bullying, the violence is so normalized on some teams that it persists for years, as players attacked one season become aggressors the next.

The AP examined sexual violence in school sports as part of its larger look at student-on-student sex assaults. Analyzing state education records, supplemented by federal crime data, AP found about 17,000 official reports of sex assaults by students in grades K-12 over a recent four-year period. That figure doesn’t capture the extent of problem because attacks are widely under-reported and not all states track them or classify them uniformly.

A detailed picture of specific incidents was revealed when the AP reviewed more than 300 cases of student-on-student sexual violence that surfaced through law enforcement records, lawsuits, interviews and news accounts. In those cases, the sports setting emerged as a leading venue for such attacks.

Teammate-on-teammate sexual assaults occurred in all types of sports in public schools, and experts said the more than 70 cases in five years that AP identified were the tip of the iceberg. Though largely a high school phenomenon, some cases were reported as early as middle school.

Serious injuries and trauma have resulted, records show. An Idaho football player was hospitalized in 2015 with rectal injuries after he was sodomized with a coat hanger. Parents of a Vermont athlete blamed his 2012 suicide on distress a year after teammates sodomized him with a broom.

The acts meet federal law enforcement definitions of rape and sexual assault, but language used by schools and coaches shrouds the problem and minimizes its severity. It also can influence whether off-campus authorities hold anyone accountable, meaning such cases don’t always show up in state education records or federal crime data as sexual assault, and no one specifically tracks or catalogs them in a systemic way.

“Language is everything,” said B. Elliot Hopkins, a sports safety expert at the National Federation of State High School Associations. “If anyone knew that their kid was going to run the risk of being sexually assaulted to be part of a team, we wouldn’t have anyone playing any sports.”

In the Gwinnett case, five to eight upperclassmen on the Parkview High School baseball team barged into the hotel rooms of freshmen teammates during an out-of-state tournament in the summer of 2015. One boy had fingers shoved through his shorts into his rectum, according to state education disciplinary records, and two others fought off similar assaults.

In disciplinary proceedings months later, the upperclassmen didn’t challenge the evidence but described what they did as “wrestling and horse playing.” Six players were expelled for times ranging from a semester to a year.

North Charleston police declined to press criminal charges after four months, classifying the assaults as minor and not worth dragging teenagers across state lines to prosecute.

A draft public statement from the Gwinnett County Public Schools initially said a player’s family had reported he was “sexually assaulted,” records AP obtained show. But the final version referred only to “inappropriate physical contact.” When asked, district officials said that wording was “more inclusive” of the “diversity of the types of misconduct alleged.”

Officials argued they didn’t have to report the incident in data the state collects on school violence because it happened in the summer. The Georgia Department of Education told AP the district was wrong and would need to correct its filing.

AP also found multiple cases where coaches fostered the opportunity for misconduct through poor supervision. Others became aware of misbehavior but treated it as a team disciplinary matter. Some failed to do anything.

In Tennessee, a freshman basketball player at Ooltewah High School, outside Chattanooga, told a coach upperclassmen used a pool cue to sexually assault him and others during an out-of-town tournament in 2015, records show.

Despite that warning, two upperclassmen went on to pin another boy down on a bed while a third one sodomized him with a pool cue, the records show. Coaches, who were elsewhere in the cabin at the time, drove him to a hospital after seeing him bleeding. The boy needed emergency surgery.

A nurse, not the coaches, contacted authorities. Investigators said the head coach instructed players to stay quiet. The head coach’s wife cleaned up and threw away the boy’s soiled clothing, “essentially erasing evidence of the crime,” investigators said.

The head coach and other school officials said in legal responses they didn’t know about the violence or seek to withhold information. The coach and his wife, who was not charged, did not respond to messages.

“If this boy had not gone to the hospital, had he not been bleeding, nobody would have known about this,” said Eddie Schmidt, a lawyer representing the player’s family.

Experts say players are indoctrinated to abusive team cultures when they’re new, transition into bystanders seeing others harmed and sometimes become attackers themselves, feeling a form of duty to uphold team “tradition.”

Some players may think enduring such acts builds team toughness, but more often, older players use sexual violence to exert dominance over newer or smaller boys vying for the roster, said Susan Lipkins, a New York psychologist and author who specializes in sports attacks.

“What’s worse for a young jock than to be emasculated to the lowest level, to be like a girl?” she said.

Athletes who are sexually assaulted feel pressured to keep quiet, experts say, because they fear speaking up could jeopardize their lineup spot or risk team success by getting other players in trouble.

Amanda Jackson’s son waited two years to tell her what he said he experienced as a freshman at Capital High School in Olympia, Washington.

After showering at a 2010 basketball camp, he was tackled by four upperclassmen who tried to penetrate him with their fingers, according to his deposition in the family’s pending lawsuit against the school district.

“I felt like if I told someone, then I would have been, you know, excluded from the team and not able to play varsity basketball,” he testified.

A psychological evaluation conducted as part of the lawsuit showed he exhibited post-traumatic stress symptoms.

“I want to get everything out there so people understand this is not normal,” his mother said.