FILE -- Marco Gutierrez, Costco photo department supervisor, holds a sign in front of the store to remind people to practice social distancing while shopping on Tuesday, March 17, 2020 in Yakima, Wash.

At least 68 staff members at Costco in Union Gap have tested positive for COVID-19 over the past week, according to the Yakima Health District.

All staff members impacted are isolating and quarantining, and Costco is conducting widespread employee testing as directed by the health district, YHD said in a press release Thursday.

During a site visit Wednesday, the health district determined there was “not an increased risk of COVID-19 transmission to the public so long as staff and customers continue to follow safety precautions,” interim health officer Dr. Larry Jecha said in a statement.

The cause of the outbreak is under investigation.

The county has seen a significant spike in COVID-19 cases in recent weeks. As of Wednesday, there were 1,118 cases per 100,000 population over the last two weeks, according to health district spokeswoman Lilián Bravo. That's significantly higher than the state goal for communities of 25 cases per 100,000 population over 14 days.

Health officials encourage community members to social distance, properly wear face masks outside the household, frequently wash hands, sanitize surfaces and stay home when sick.

Reach Janelle Retka at jretka@yakimaherald.com or on Twitter: @janelleretka