The majority of the cases popped up at Tesla’s Fremont, Calif. factory, according to Tesla blog Electrek. The facility was the focal point of a standoff between CEO Elon Musk and California authorities, who forced it to shut down under statewide lockdown orders.

Internal data obtained by the blog shows that a majority of employees who may have been exposed to the virus did not subsequently receive a COVID-19 test. More than 130 employees have tested positive for the virus.

Exposures to the virus have spiked in recent days, with more than 250 people exposed in each of the past two weeks — up from less than 50 a month ago.

While Tesla has implemented measures meant to keep employees safe, such as temperature checks and mandatory social distancing, employees told the blog that rules are not always followed.

The Washington Post reported in June that half a dozen anonymous Tesla workers said that the Northern California factory was lax in enforcing its safety measures, including the sanitation of machinery.

The report alleged that factory employees are “hovering over each other,” and that there is a lack of communication between management and staff regarding coronavirus cases among workers. Employees disappear for weeks at a time, according to the report, with supervisors saying only that they were “sick.”

Tesla reopened its factory last month against Alameda County orders after a prolonged standoff with state health officials. Musk had railed against the coronavirus lockdown, calling it “fascist” and saying the government was “forcibly imprisoning people in their homes against all their constitutional rights.”

The billionaire chief executive has previously downplayed the seriousness of the pandemic, calling it “dumb” in early March.

The company last month laid out a plan for reopening factories, publishing a 38-page “Return to Work Playbook” that called for a wide range of precautions to keep plants clean and prevent the coronavirus from spreading among workers.

“We will continue to put people back to work in a safe and responsible manner,” Tesla said in May.

Shares of Tesla were up 1.8 percent Tuesday afternoon, trading at $1,524.29. The automaker’s stock is up more than 250 percent this year.