Tesla Inc. stock plunged more than 15% as its vehicle factory in California appeared to be operating normally on Wednesday despite an order by local officials to comply with a three-week lockdown in the San Francisco Bay Area to rein in the spread of coronavirus.

Thousands of cars were visible in the factory's employee parking lot in Fremont, California, and employees were going to work, Reuters witnesses said. Several 18-wheeler container trucks were seen pulling into the factory grounds, they said.

There were also at least two food trucks parked in front of the factory building and workers were seen walking back from a restaurant across the street, Reuters reported.

Alameda County, where the factory is based, is one of six covered by an order from regional officials to "shelter in place," which limits activity, travel and business functions to only the most essential, and advises people to stay home except for the most crucial reasons.

The county sheriff's office on Tuesday afternoon said Tesla is not considered an essential business under that order and cannot continue to operate its factory normally.

Tesla can only maintain minimum basic operations under the order, the sheriff's office said. Under the county's order, those include maintaining the value of inventory, ensuring security and processing payroll and employee benefits.

After the Alameda County decision that Tesla should quit factory work, the company sent an email to employees in which it said that essential activities, including production, would continue, according to a person who saw the memo.

However, Bloomberg reported that Tesla’s human-resources chief told employees early Wednesday the company is awaiting “final word” on the status of operations at the plant.

Several workers verified receiving the email from Valerie Workman, the carmaker’s head of human resources for North America, Bloomberg said.

Representatives for Tesla had no immediate reply when contacted for comment.

Tesla's Fremont facility, which is the company's sole U.S. auto factory, employs more than 10,000 workers and had an annualized production of slightly more than 415,000 units by the fourth quarter.

Roughly 10,000 employees work at the Fremont plant, where Tesla makes the Model S, X and Model Y.

The San Francisco Bay Area has taken stringent measure to slow the spread of the coronavirus, with more than 7 million residents urged to stay at home except for exercise or quick trips to the grocery store.

According to the county’s order, businesses deemed non-essential are restricted to “minimum basic operations,” which Tesla appears to be defining broadly to include assembly line production activity.

A spokesman for the sheriff's office on Wednesday said rumors on social media that it had sent officers to Tesla's Fremont plant were not true. He referred further questions to the local police department, which did not immediately respond to a request for comment.

The offices of Fremont mayor's and the Alameda County district where the factory is located did not immediately reply to a request for comment.

The California governor's office did not immediately respond to a request for comment on the situation.

Under Alameda County's lockdown order, which took effect on Tuesday, violating or failing to comply are misdemeanors punishable by fine, imprisonment, or both.

On Tuesday, a spokesman for the county sheriff's office declined to provide details on any enforcement measures the sheriff's office would take if Tesla defied the order.

Prior to the sheriff's office's decision, Tesla told employees in an email that the company and its suppliers would continue operations supporting the manufacturing and delivery of vehicles, a person who had see the email told Reuters.

Tesla stock (TSLA)  closed at $361.22, down $68.98, or 16%, Wednesday.