DETROIT — A gasoline leak at Ford Motor Co.’s Flat Rock, Mich., assembly plant is likely the cause of vapors and gasoline found in the city’s sewer system, prompting a state of emergency in the area, southwest of Detroit, the company said.

The factory, where the Ford Mustang is built, is closed through the Labor Day weekend as previously planned while Ford continues to investigate the matter. The leak and Ford’s role were first reported late Friday by The Detroit News.

“We take our responsibilities as a corporate citizen and to protect the environment seriously,” Bob Holycross, Ford’s vice president for sustainability, environment and safety engineering, said in a statement. “We’ve been working with city, state and federal agencies over the last several days to understand and address the issue in Flat Rock.”

The News, citing the Michigan Department of Environment, Great Lakes and Energy, said an estimated 1,000 to 3,000 gallons of unleaded gasoline are thought to have spilled into the city’s sewer system. Local officials as well as Michigan Gov. Gretchen Whitmer declared a state of emergency in the area, prompting evacuations at a charter school as well as multiple homes.

Ford said last week it discovered “what originally looked to be a relatively small leak in a pipe that carries gasoline used to fuel vehicles built at the plant.”

The company shut down the fuel pipe and notified local and state officials, but believed the leak was contained to the property. It was later found to be larger than believed.

“We’re urgently addressing the matter; there’s more we need to know in order to confidently develop and implement a corrective plan,” Ford said.” The plant will be closed through the Labor Day weekend. “As a precaution, we’re in the process of isolating wastewater on our property from the city’s system,” the company said. “Ford is assisting government officials as cleanup work begins in the community.”