JAY, Maine (AP) — State and federal investigators began digging into the cause of a Maine paper mill explosion that sent debris and a slurry of chemicals raining down on nearby cars and buildings.

The mill was shut down indefinitely as elation over the stunning news that that no one was harmed shifted to worries Thursday about the future of the mill that employs 500 people and is the town's largest taxpayer.

“We are not in a position to estimate the exact timing of restarting any part of the mill,” said Roxie Lassetter, a company spokeswoman.

The blast happened in a 70-foot-tall, kettle-like device called a “digester” that contained a slurry of wood chips, water and chemicals. Nearby vehicles were covered with a thick, brown substance that fell from the sky after the blast.

But the massive paper machines that churn out different types of specialty paper escaped damage, and the company is exploring options to get them running as soon as possible, Lassetter said.

Around the town of 5,000, residents who've become accustomed to ups and downs in the paper industry understand that viability of the mill depends on the extent of the damage.

“All of the options have entered everyone’s minds. Right now we’re trying to focus on the positive,” said Town Manager Shiloh LaFreniere.

The positive includes the fact that none of the 200 workers at the mill were hurt at the time of the blast, LaFreniere said.

Also, the Maine Department of Environmental Protection classified the slurry that rained down as a minor irritant that wasn't considered to be toxic, she said. Public works crews were sweeping the streets and picking up fallen debris on Thursday.

The investigation into the cause of the blast was led by a team of investigators from the Fire Marshal’s Office and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives, said Stephen McCausland, spokesman for the Maine Department of Public Safety.

The mill survived a post-recession paring that wiped out several paper mills in rural Maine.

The mill, which was built in the mid-1960s, changed ownership in February when it was sold by Ohio-based Verso to a Pennsylvania company, Pixelle Specialty Solutions.