Five men’s lacrosse players at Tufts University remain hospitalized after a voluntary supervised 45-minute Navy SEAL-style workout left them with a dangerous condition called rhabdomyolysis.

After nine men’s lacrosse players were hospitalized with serious medical conditions following a workout led by a recent Navy SEAL graduate, Tufts University says they’re appointing an independent investigator to figure out what happened.

BOSTON (AP) — A dozen Tufts University men’s lacrosse players have been diagnosed with a rare muscle injury after participating in a voluntary, supervised 45-minute workout that the team conducted, a university spokesperson said Friday.