CINCINNATI — A dangerous chemical leak at a railyard near Cincinnati forced nearby schools and residents to evacuate Tuesday as officials warned of a possible threat of an explosion.

Emergency officials continued to work at the scene of a railcar leaking styrene on Tuesday night in Whitewater Township near Cleves, just west of Cincinnati. Around a dozen agencies, including the Greater Cincinnati Hazardous Materials Unit, responded when the railcar started leaking, said Mike Siefke, chief of Little Miami Joint Fire and Rescue District.

Styrene is a flammable gas and can be fatal if inhaled. The chemical is also considered a probable human carcinogen that can damage organs, inflame lungs, and make it hard to breathe, according to previous reporting from the Cincinnati Enquirer, part of the USA TODAY Network.

Officials said the initial call related to the chemical leak went out at 12:46 p.m. Tuesday and a spokesperson for Central Railroad of Indiana was notified around 1 p.m. that the railcar was venting styrene. The railroad does not own the railcar but it was on the company's property, the spokesperson added.

Residents near Cleves were urged to leave their homes due to the chemical leak, according to the Hamilton County Emergency Management Agency. Officials have yet to say what railroad was transporting the chemicals or if any other hazardous chemicals were being stored on board.

No civilian or firefighter injuries were reported. Siefke said a few residents have sought medical attention, but he did not know how many or for what they were treated.

Transportation Secretary Pete Buttigieg said personnel from the Federal Railroad Administration were en route to the incident. The Ohio EPA said its Emergency Response team was at the scene to assist local emergency responders, adding that the volume of styrene released is still unknown.

At a 10 p.m. briefing Tuesday, Siefke said there are still concerns about a possible explosion, although the car's temperature has been lowered by spraying it with water.

'Could’ve been a lot worse'

Siefke said that air monitoring for styrene had begun as officials attempted to collect data to determine whether the evacuation and shelter-in-place orders were set appropriately. Currently, the radius for evacuation is a half mile from the leaking car.

The first results from the air monitoring will be known by early Wednesday, which is expected to determine if the radius of the shelter-in-place order should be changed from its current three-quarters of a mile.

Officials initially told residents to stay indoors and seal off doors and windows, and later issued an evacuation order for some. A shelter was opened at the Whitewater Township Community Center, where officials said about a half-dozen people were sheltering there.

Andrew Knapp, director of the Hamilton County Communications Center, said that there are about 210 residential households in the half-mile evacuation circle.

"So we’re very fortunate there are a limited number of residential homes," Knapp said. "It could’ve been a lot worse if it were somewhere else.”

Local schools were also evacuated Tuesday afternoon after the railcar began venting styrene. Three Rivers Local School District said on its website that the district will be closed on Wednesday.

Some residents displaced

Charlie Davis, 74, was watching a movie in his Hooven home when he heard banging on the door. A police officer was going door to door on his street warning residents of the evacuation order.

When he came outside, he said the air smelled of gasoline and his eyes started to burn. “I know people who ignored (the evacuation order), but not me. I’ve got too many health problems,” he said.

Charles Garner, 58, a Hooven resident, said he was visiting downtown when the order was placed. He couldn’t make it home because U.S. Route 50 was shut down. His 92-year-old mother, also a Hooven resident, had to leave her home and was taken to the shelter. 

Cincinnati styrene leak caused concern in 2005

In August 2005, styrene began leaking from a railcar in Cincinnati's East End. That also was not the result of a derailment, but the leak forced evacuations and shelter-in-place orders for residents.

After two days of fear that the 30,000-gallon tank car could explode, hazmat teams were able to contain the leak. A railcar had been left sitting over the summer for more than five months, leading the styrene inside to heat and leak out.