A massive fire involving large oil tanks at a Montgomery County, Maryland, quarry Thursday sent thick clouds of black smoke billowing into the sky that could be seen for miles around.

“The good news is, the fire is out. There were no injuries,” Montgomery County Fire and Rescue spokesperson Pete Piringer said during an evening news conference.

There was no danger to the surrounding communities or the public, but the heavy smoke initially prompted air quality concerns, he said.

The fire was at the F.O. Day Bituminous Company asphalt plant at the Rockville quarry at 13900 Piney Meeting House Road. Firefighters were dispatched to the quarry around 11:45 a.m.

The fire involved two tanks of liquid asphalt and one tank of used motor oil, as well as a conveyor belt and other large equipment, Piringer said.

By 4 p.m. Piringer said crews had made “significant progress” in putting the flames out. A hazmat team and crews with the Maryland Department of the Environment worked to shut off natural gas to a boiler that was feeding the fire, he said.

Because the fire involved asphalt, which is made from petroleum, firefighters could not use water and had to use other means, such as foam, which essentially smothers the flames.

Piringer said a foam crash truck from Dulles Airport helped finish putting out the fire.

The cause of the fire was not yet known, he said.

While air quality was a concern, Piringer likened it a Code Yellow from the Environmental Protection Agency and said it was “nothing more than bad air pollution day.” He said people should limit their time outdoors and close their windows if they live nearby.

All of the workers were evacuated from the plant and no one was injured in the fire, Piringer said.

Footage from SkyTrak7, the news helicopter operated by 7News, showed the tanks burning, with black smoke billowing above the flames.