Evacuation and shelter-in-place orders are in place after a styrene leak at a Cleves railyard Tuesday afternoon.

Officials said late Tuesday that the railcar had stopped leaking the dangerous chemical but that residents were to remain out of the area, according to Enquirer media partner Fox19.

Several schools in the area are closed Wednesday.

The source of the leak is a railcar at U.S. Route 50 and State Route 128, west of Cincinnati, that holds styrene, a toxic and highly flammable chemical. Officials expressed concern that the leak could cause an explosion.

Here's what we know so far about the styrene leak:

Evacuation order remains in place

People living within a half-mile of the area of the railcar were told to leave their homes and those just outside the area were told to keep their windows closed.

Mike Siefke, chief of Little Miami Joint Fire and Rescue District, previously said the threat of explosion stemming from a rail car's leak of styrene is not imminent but a very real concern.

"I am more concerned knowing what we know now," Siefke said.

No civilian or firefighter injuries were reported as of Tuesday evening.

What is styrene?

The chemical that leaked from the railcar is a toxic and flammable gas that is used to make plastic, paint and rubber.

The colorless gas has a sweet order. It can cause headaches and nausea and make it hard to breathe. Long-term exposure to the gas can damage organs.

What is styrene?What to know about the toxic chemical spurring Cleves evacuation

The chemical has been linked to cancer and it's been listed as a human carcinogen by the National Toxicology Program and the National Academy of Sciences.

How did the leak happen?

At 12:46 p.m., a call related to the chemical leak at a railyard west of Cincinnati was made to officials.

The Central Railroad of Indiana was notified shortly after that a rail car on its property was venting styrene. The railroad does not own the railcar, a railroad spokesperson said.

At roughly 2 p.m., the Hamilton County Emergency Management Agency alerted the public via social media. The agency initially told residents to stay indoors and seal off doors and windows. An hour later, officials urged everyone within a half-mile radius of the railyard by U.S. Route 50, state Route 128 and Valley Junction Road to immediately leave the area.

A shelter-in-place order was put in effect for residents within three-quarters of a mile from the leak Tuesday afternoon.

Around a dozen agencies, including the Greater Cincinnati Hazardous Materials Unit, responded to the scene, Siefke said. The Ohio EPA said its Emergency Response team arrived around 4 p.m. to assist local emergency responders.

Officials have not said what caused the train car to start venting styrene but Siefke said the leak was not caused by a train derailment.

How are crews controlling the leak?

Crews are working to cool down the rail car by applying water to its tank, with explosion concerns stemming from elevated temperatures within the rail car, Siefke said.

He said they did not know why the car had stopped leaking, Fox19 reported.

Brian Stussie, of Genesee & Wyoming Railroad, said crews managed to separate the leaking rail car from the rest of the train. He said there were other cars connected to the train carrying the same chemical, styrene, according to the Fox19 report.

“We removed the remaining cars that were coupled to the car in question,” Stussie said. “We’re monitoring the temperature as we speak and we’re using water to keep the car cool.”

Transportation Secretary Pete Buttigieg said personnel from the Federal Railroad Administration are en route to the incident.

When will the evacuation order be lifted?

Siefke said air samples are being collected and tested.

The first results from the air monitoring will be known by early Wednesday, and that will determine whether the evacuation and shelter-in-place orders will be changed.

The Hamilton County Emergency Management Agency issued an evacuation order for a half-mile area around the rail car that was leaking styrene. Residents within a three-quarters-mile area were told the stay indoors and seal off windows and doors, close fireplace dampers, and turn off the heat.

How are schools in the area affected?

Three Rivers School District evacuated students and staff from school buildings and canceled all after-school activities Tuesday evening. District officials announced schools in the district are closed Wednesday.

How have residents responded?

Just before 4 p.m., around a half-dozen people were at the Whitewater Township Community Center, where residents have been encouraged to take shelter while an evacuation order remains active.

Charles Garner, 58, a Hooven resident, said he was visiting downtown when the order was put in place. 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.

Another shelter was set up at the Miami Township Hall at 112 South Miami Ave., officials said.

Charlie Davis, 74, was sitting in his Hooven home watching a movie 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 burning. “I know people who ignored (the evacuation order), but not me. I’ve got too many health problems,” he said.

Who owns the railcar?

The railcar is located on property owned by Central Railroad of Indiana, a subsidiary of Genesee & Wyoming Inc., which owns or leases more than 100 railroads across North America. Central Railroad of Indiana did not immediately reply to The Enquirer's request for who owned the railcar.

Where is Cleves?

Cleves is a village located on the West Side of Hamilton County and 16 miles west of downtown Cincinnati. The village encompasses 1.6 square miles and has a population of 3,414 residents according to the 2020 U.S. Census.

Has this happened before?

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