Fire crews were on the scene of a fire at the Delaware City Refinery in New Castle.
The one-alarm fire broke out around noon on Sunday, in the crude unit.
One firefighter was transported to a local hospital with non-life threatening injuries.
"Although everyone who was working on the unit is safe, accounted for and there were no injuries, a firefighter from New Castle County responding to the incident is being treated for a non-fire related medical condition," said Lisa Lindsey, Public Information Officer with Delaware City Refining Company.
"Thankfully, it's a Sunday, so some of the schools that are close by are closed. Our traffic patterns are pretty low. We're not detecting anything off the sight, at this current time, but we continue to deploy additional air monitoring equipment to make sure the public is safe," stated Chief Jamie Bethard, with the Department of Natural Resources and Environmental Control.
Fire officials say the fire is still burning, though the fire poses no threat to the unit, the people working there or the public, according to officials.
Environmental officials say they will be staying on the scene until the fire is out and the area is declared safe. They will be monitoring the air throughout.
The cause of the fire remains under investigation.