The Aspen Daily News reports that state and city environmental health officials have been unable to determine what caused 32 people to fall ill after dining at Aspen restaurant L’Hostaria two weeks ago, although tests have shown that whatever caused it most likely wasn’t related to the food.

The Colorado Department of Public Health and Environment has been running numerous tests on stool samples from affected people, all of which have turned up negative, said food-borne and enteric disease coordinator Alica Cronquist on Thursday. The lab is still investigating the matter, she said.

Two weeks ago, 32 patrons that dined at L’Hostaria over two nights became ill. Symptoms included vomiting, diarrhea and stomach ache, city of Aspen environmental health specialist C.J. Oliver said. Tiziano Gortan, who owns the high-end Italian restaurant in downtown Aspen, said the illness had nothing to do with the food, but was caused by a person-to-person virus that had been spreading through the community at the time of the outbreak.