About 12,000 people were evacuated from a Missouri stadium after a gas odor was reported on Friday evening, but no leak was detected, St. Louis fire officials and gas utility The Laclede Group Inc. said.
The crowd funneled out of the Edward Jones Dome, the home of the St. Louis Rams National Football League team, after about 9 p.m. local time (0200 GMT), the gas utility and the St. Louis Fire Department said in a statement.
Two people were treated at the scene and one was sent to hospital, all with unspecified injuries, it said.
People attending a beauty convention began leaving on their own after they got whiffs of the smell of burning plastic and then gas, local media reported.
Fire officials also ordered people away from the downtown building for at least an hour while Laclede ran tests which ultimately found no natural gas leak, fire officials and the company said.
"We don't know what the source is but we do know it's not natural gas," said Jenny Gobble, a Laclede spokeswoman.
(Reporting by Eric M. Johnson in Seattle; Editing by Pravin Char)