HONOLULU (AP) — Up to 45 people have become sick after dining at a Honolulu restaurant where six cases of norovirus were confirmed, Hawaii Department of Health officials said.

Herringbone Waikiki voluntarily closed on Thursday after health department officials said people who dined at the restaurant fell ill. All recovered after a couple of days.

"Exposure appears to have been limited to those dining at the restaurant over the past weekend," department spokeswoman Janice Okubo told the Honolulu Star-Advertiser. "The investigation is still underway with lab test results pending."

Restaurant spokesman Rob Mora said they have worked closely with the health department since the illnesses were reported, and the health of their guests remains their top priority. Food safety inspectors cleared the restaurant for reopening on Friday after it was thoroughly cleaned.

"In alignment with the Department of Health, we cleaned four times everything top to bottom, up to seven feet," Mora said.

Health department officials launched an investigation after receiving a report on Monday from a person who said a group of five all became sick after dining at the restaurant, which is near the iconic Waikiki Beach lined with high-rise resorts. Inspectors visited the restaurant on Tuesday to investigate and collect samples.

All restaurant staff will undergo training regarding hygiene, Mora said.

Norovirus is a leading cause of illnesses from contaminated food, and employees infected by it are frequent sources of an outbreak. Stomach ache, vomiting and diarrhea are common symptoms of the highly contagious illness, according to the U.S. Centers for Disease Control and Prevention.