A tanker holding 23,000 gallons of hydrochloric acid leaked at a Columbus rail yard, prompting authorities to close the yard and evacuate nearby businesses and homes.
No injuries were reported.
Authorities blame the collision of two tanker cars for the leak. News helicopter footage shows a river of yellow-green acid running from the railroad car along the tracks. White plumes of vapor are drifting from the area as well.
Fire officials say the problem was first reported to them around 11:00 am.
Police spokeswoman Sherry Mercurio says she was unsure exactly how many people were evacuated.
State health officials say the acid is more dangerous as a gas and irritates the eyes and respiratory system. Prolonged exposure to high concentrations of the gas can be fatal.