Firefighters said part of a freight train that derailed and exploded in flames in Columbus was carrying ethanol.

The Norfolk Southern train was heading south when about a dozen cars derailed in the northern part of the city, near the Ohio State Fairgrounds.

Assistant Chief David Whiting said three of those cars were tankers carrying ethanol. In addition, officials said the train was carrying grain, corn syrup and another dangerous element, styrene. Norfolk Southern officials said styrene can be dangerous if it ignites, but they said no cars containing styrene derailed.

Norfolk Southern said it wasn't immediately clear what caused the derailment. Authorities decided to let the fire burn out instead of trying to extinguish it, and two tanker cars carrying ethanol burned throughout the day.

The fire prompted the evacuation of a two-block area, which affected about 30 homes. Evacuees were taken to a shelter set up by the American Red Cross. All other residents within a one-mile radius were urged to stay in their homes.

Witnesses reported seeing the explosion 10 miles away from derailment site around 2 a.m. Wednesday. Joel Priester watched the blast from his home two blocks away and said it "looked like the sun exploded."

A fire official says two people who ran toward the scene before the explosion were injured but were able to take themselves to a hospital. No personnel on the train were injured.

All rail traffic in Columbus came to a standstill after the crash and while the train cars burned throughout the day. Wednesday afternoon, Norfolk Southern officials were directing trains away from the area.

NEWS9's Kelly Camarote was in Columbus on Wednesday following this story. Stay with WTOV9, WTOV9.com and WTOV9 Mobile for continuing coverage.