All Oahu and Kauai Genki Sushi restaurants remained closed Tuesday after the Department of Health determined the likely source of the hepatitis A outbreak was imported frozen scallops served raw at the restaurants.

The restaurants were closed “to prevent any further illness and protect the public,” said Janice Okubo, the department’s communication director, in a Monday night press release.

There are 10 Genki Sushi restaurants on Oahu and one on Kauai.

“The Hawaii State Department of Health is confirming that distributor True World Foods did not send the implicated frozen imported scallops to the Maui and Hawaii Island Genki Sushi restaurants,” the department said in a Tuesday press release.

“DOH health inspectors were able to embargo the implicated frozen scallops at the True World Food warehouse on Oahu before it was distributed.”

The “product of concern” was identified as Sea Port Bay Scallops (Wild Harvest, Raw Frozen) that originated in the Philippines (“Product of the Philippines” is printed on the box), distributed by Koha Oriental Foods on Oahu and Kauai.

As of last count, 168 people had been infected in the outbreak since it began in June, most of them on Oahu. It’s the worse hepatitis outbreak in more than two decades in Hawaii, department officials have said.