(NEXSTAR) — An estimated 145 employees at a Costco in Washington State were infected with the coronavirus, local officials said.

The Costco currently remains open and site-wide testing is ongoing.

According to the Yakima County Health District, in which the Costco is located, all employees at the site are being tested for the virus. Those infected have been sent home to isolate and quarantine.

Officials noted that the “sharp increase in cases mimics the type of activity that happens after some sort of superspreader event,” but did not identify this particular incident as a superspreader.

Melissa Sixberry, the Director of Yakima County Disease Control, said she anticipates that the number of cases will continue to rise as results are received.

“At this point in time, all positive cases have been identified and sent home,” added Dr. Larry Jecha, Interim Health Officer for Yakima County. “Weekly site- wide testing will ensure that any new cases that occur, will be promptly identified, and those staff members will also be directed to isolate and quarantine. This, in addition to ensuring that Costco, and its shoppers, continue to follow the proper COVID-19 safety precautions, will mitigate the risk for potential COVID-19 infection.”

Costco representatives did not immediately respond to a request for comment.

On its website, the big-box retailer said it is “closely monitoring the changing situation and complying with public health guidance.”

Protocols to keep shoppers and employees safe include limiting the number of people at each location, encouraging social distancing, reducing some services (such as samples) and sanitizing surfaces.