Twelve members of the Tufts University men’s lacrosse team were diagnosed with rhabdomyolysis, a potentially life-threatening condition, following a voluntary workout the team held Monday on campus.

Five players were hospitalized as of Saturday, according to university spokesperson Patrick Collins, who said the number of confirmed cases and those hospitalized could change. The voluntary, supervised 45-minute workout was led by a Tufts alum and a recent graduate of Navy SEAL training, Collins said.

Rhabdomyolysis, or rhabdo, occurs when damaged muscle breaks down rapidly, causing the release of proteins and electrolytes into the bloodstream, which can lead to complications that include kidney failure, permanent disability or death, according to the Centers for Disease Control and Prevention.

In 2011, 13 University of Iowa football players were hospitalized with rhabdo following a strenuous offseason workout. William Lowe, one of the players, settled a lawsuit in 2016 against university officials for $15,000. In 2016, eight volleyball players from Texas Woman’s University were hospitalized with the condition after an annual fitness test.

In 2017, three Oregon football players were hospitalized, including one who was diagnosed with rhabdo, following “a series of grueling strength and conditioning workouts,” according to the Oregonian. The university later suspended its strength coach and issued an apology on behalf of its athletic department. In the Oregon case, the workouts were described “as akin to military basic training, with one said to include up to an hour of continuous push-ups and up-downs.” Some players subsequently said the severity of the workouts had been exaggerated and that they were difficult but not out of the ordinary.

The nature of Monday’s workout at Tufts, which included around 50 players, is unclear. Collins said the university will appoint an independent investigator “to conduct a thorough review as quickly as possible, with a goal of taking any steps needed to support the safety of our student-athletes.”

Tufts, which competes at the NCAA’s Division III level, won its fourth national championship in May.

“Our thoughts are with the players and their families, and we are hoping for their quick return to good health under the care of local medical experts,” Collins said. “Meanwhile, we are closely monitoring the condition of the rest of the team and have postponed all team practice activities until each team member has been evaluated and medically cleared to return to participation.”