State health officials are investigating what appears to be an outbreak of Norwalk virus, likely from a restaurant on Oahu’s North Shore.

State epidemiologist Dr. Sarah Park said at least 35 people have reported symptoms resembling norovirus, which is also known as Norwalk virus. It causes nausea, diarrhea and other symptoms.

While it was previously believed the outbreak stemmed from a large bicycle ride Sunday, Park says the common link appears to be Cholo’s Homestyle Mexican in Haleiwa. Restaurant owners were not immediately available for comment.

The restaurant voluntarily closed briefly on Tuesday for a cleaning. Park says the restaurant reopened after a sanitation inspection.

Norwalk virus is an infection that causes nausea, vomiting, diarrhea and abdominal cramps, but without fever.

Officials say laboratory confirmation is pending.