BETHEL — CSX investigators are returning to the scene of a train derailment to try and figure out what caused more than a dozen cars to leave the tracks. EPA investigators will also be on hand to look at the environmental impact of the incident.

Black smoke, containing potentially hazardous chemicals, billowed into the air most of the day after a freight trained derailed in northern Pitt County Tuesday.

The CSX freight train went off the tracks and caught fire between the towns of Bethel and Stokes about 7 miles north of Greenville. The train derailed around 10:40 a.m. near Whitehurst Station.

The CSX train appears to have crashed on a bridge above a small creek. CSX says it inspected that same bridge Tuesday morning.

Fifteen of the 38 cars derailed and their hazardous materials are flowed into a creek.

Smoke from the burning wreckage compelled officials to evacuate over 50 homes near the crash site. Residents were allowed to return just before midnight.

"Anyone who is living downstream of this needs to keep their animals and their children away from it," said Arlen Holt, Pitt County spokesman.

Officials say they were concerned about fumes from chemicals that were in some of the burning cars.

At first, crews planned to let the chemicals continue to burn, but then discovered a third chemical, dichloropropene, in a car that had not ruptured.

State HazMat teams and local fire departments wanted to keep that car from burning, so they used 1,600-gallon vats of water to cool down all of the cars.

The Pitt County Sheriff's Department closed highways 11 and 30 soon after the derailment.

Three of the chemicals that spilled in the train derailment are found in a lot of products we use.