The tank car contained about 1,600 gallons of Sodium Hydroxide - also known as caustic soda or soda lye. If inhaled, it can be fatal and serious skin burns are possible.
Pictures from the scene show the end of the car is crumpled. Officials said the accident happened while Norfolk Southern rail workers were trying to couple two cars together. The couplings missed and the cars slammed together.
Officials set up a 150 foot isolation zone around the area and diverted traffic. One home nearby is said to be out of harm's way. Other trains were still able to pass by, but everyone else was kept at a distance.
"We haven't had to evacuate any houses, the leak is contained within the tracks of railroad," Durham Assistant Fire Chief Dan Curia said.
The Norfolk Southern train was on the way to Brenntag Chemical in Durham.
Workers used sand trucks to create a barrier between the leak and a storm drain about 75 feet away. Otherwise, there was a small chance the chemical could enter into the city’s drinking water. Before any cleanup began keeping the harmful chemical away from the drain was priority.
"The city is bringing in a sand truck to build a dyke to keep the product out of the city water system, which we don't anticipate that being a problem," Curia said.
At the height of the spill, officials said the Sodium Hydroxide was pouring out of the tanker at about 15 gallons per minute. Crews had to bring in an empty car to offload the product and then carefully clean up the affected soil.