BERKELEY — Paralyzed Cal rugby player Robert Paylor was injured last month by an illegal hit that was caught on film, storied head coach Jack Clark said this week in a development that has launched a USA Rugby investigation.

The candid June 2 statement by Clark called Paylor’s injury in the May 6 Varsity Cup championship win against Arkansas State “preventable.”

“Robert’s injury was preventable,” Clark said. “It was the result of illegal foul play. There is end-goal video footage as well as photography that makes this indisputable. Those materials are now in the hands of USA Rugby, which has opened an investigation into the incident.”

USA Rugby Collegiate Director Rich Cortez confirmed an investigation had been launched Thursday, saying a “committee was looking into it.” He referred any specific questions to CEO Dan Payne, who did not immediately return a request for comment.

Reached by email late Thursday, Shaun Potgieter, the coach of Paylor’s opponent Arkansas State, said “Our thoughts and prayers go out to the Cal rugby program and player injured in this year’s title game. Words are often inadequate to express our feelings when we see a tragic accident in sports like this one.”

On June 1, Paylor was transferred from his Santa Clara hospital to Craig Hospital in Englewood, Colorado, to start rehabilitation on his “significant paralysis,” Clark said.

“He’s had an operation to stabilize his spine, after which he battled the onset of pneumonia, high blood pressure and difficulty swallowing, resulting in the necessity of a feeding tube,” the coach said. “Throughout this truly difficult period, Robert has been a champion, battling every day to restore his health in order to be cleared by doctors for the next stage of his rehabilitation.”

Clark released the statement two days before Cal won the Collegiate Rugby Championship 7s in Philadelphia, the school’s fifth straight national 7s title and 33rd national championship overall.

Since the injury, almost $680,000 has been raised for Paylor in a GoFundMe account hoping to raise $1 million for his continued care.

In response to Clark’s claims of an illegal hit, Cal rugby fans chimed in on the team’s Facebook page.

“I hope the young man that committed this egregious foul learns from this experience. I pray for healing of all those concerned, most especially Robert,” one wrote.

“If Robert’s injury was the result of a preventable act of foul play it is all the more tragic, and a further reminder (though none should be needed) that such cannot be tolerated in the game,” wrote another.