BATH — Bath Iron Works, one of the state’s largest employers, says three employees in a Brunswick facility tested “potentially positive” for COVID-19 last week.

According to BIW spokesman David Hench, the employees work at the company’s structural fabrication facility, also called the Harding Plant, on Bath Road in Brunswick. Hench declined to say whether the three employees work on the same shift or near one another.

Two of the employees tested positive on Saturday and were last at work on Wednesday and Friday, respectively. The third was last at work Friday.

In a statement posted online, the company stressed the three employees are “considered ‘potentially positive’ because positive test results were acquired by ‘rapid-testing’ that is less reliable than PCR [polymerase chain reaction] tests used to determine positive status in accordance with CDC guidelines.”

Dr. Nirav Shah, director of the Maine Center for Disease Control and Prevention, said from what he’s seen of the rapid tests, a negative result is reliable, but a positive may be a false positive, the Portland Press Herald reported.

Regardless of how the employees tested positive, the company has started contact tracing and disinfecting the facility.

“BIW continues to follow best practices for reducing the risk of virus transmission and expects all its employees to adhere to those guidelines, especially now as we enter the winter months and as the rate of transmission appears to be climbing in Maine and throughout the country,” Hench wrote.

Hench said the Maine Center for Disease Control and Prevention is aware of the company’s new cases, but Maine CDC Spokesman Robert Long said the department “has not opened a new outbreak investigation at Bath Iron Works.”

“All confirmed COVID-19 cases are investigated, and part of that investigation involves exploring links to other cases that could demonstrate transmission at a shared site or time,” Long said. “If case investigations reveal epidemiological links between three or more cases at the shipyard or one of its facilities, an outbreak investigation would be opened.”

Hench said the company didn’t yet know the source of the new cases or whether they’re connected.

BIW, a subsidiary of global aerospace and defense company General Dynamics, has required employees to wear face masks when near others since October, something the CDC has said can help mitigate the spread of COVID-19.

“BIW workers – and all Maine people – can wear face coverings, stay at least 6 feet apart, and avoid non-essential gatherings or travel to limit potential spread of the virus that causes COVID-19,” Long said.

The shipyard has avoided widespread COVID-19 outbreaks since the pandemic reached Maine in March. Since then, 21 employees, have tested positive for COVID-19. Most recently, two BIW workers from the main shipyard in Bath tested positive for COVID-19 last week, according to the company’s website.

While Brunswick had seen just 78 COVID-19 cases as of Tuesday, BIW employs 6,800 workers from every county in the state.

Maine has seen a sharp increase in cases within the past few weeks. On Tuesday, the Maine CDC reported 246 new cases, the second highest daily new case total to date. That case count is just two cases shy of the single-day record, set last week.

As of Tuesday, 9,363 Mainers have tested positive for COVID-19. Of those, 7,025 have recovered and 166 have died.