At least 15 spectators at an Indiana racetrack were taken to a hospital and hundreds more evacuated from the site because of a chemical leak nearby, officials say.

The leak, determined to be sulfur dioxide, came from the Hydrite Chemical Company on Terre Haute's south side close to the Hulman-Mini Speedway where a crowd was watching quarter-midget auto racing the evening of Aug. 15.

Winds carried fumes from the chemical company toward the race track.

"I was in the bleachers watching races," a young spectator told a local television station, "and I started smelling stuff and people started evacuating, so I guess I followed."

Workers at the chemical company located the leak and quickly worked to shut off some pipes, the station reported.

"People complained of some breathing difficulty and burning skin," said Joe Swan of the Terre Haute Fire Department, adding that 15 were taken to a local hospital suffering from "bronchial irritation."

Other symptoms reported by some of the evacuees included nausea and a metallic taste in the mouth; oxygen was administered to some people by first responders.

Emergency workers and police evacuated people from the track and the surrounding area while hazmat and fire personnel cleared the area, reopening it after 2 hours.

"We believe Hydrite's got everything shut down and there's no leak at this time," Swan said.

Of the 15 people taken to Terre Haute Regional Hospital, 12 were released after treatment while three were admitted for some more tests, the hospital said in a statement.

"We do drills for situations like this, and we handled the real-life situation very well," said Chief Nursing Officer Angela Ellis.

Exposure to sulfur dioxide can cause "an array of adverse respiratory effects including bronchoconstriction and increased asthma symptoms," according to the U.S. Environmental Protection Agency.