The New York Metropolitan Opera stopped a performance Saturday afternoon after someone in the audience sprinkled white powder into the orchestra pit during an intermission before the final act of Rossini's "Guillaume Tell."
As anti-terrorism police investigated the incident, the Met canceled a scheduled evening performance of "L'Italiana in Algeri," also by Rossini. No injuries were reported and no one was taken into custody.
The police said they had not yet identified the "unknown substance" tossed into the orchestra pit, and no witnesses stepped forward with further information.
Audience members said there was some confusion as Met officials first said a technical issue was delaying the fourth act of the opera. After a further delay, the audience members were told to go home. Some noticed police entering the hall.
Dylan Hayden of Toronto, who was seated near the rear of the ornate hall, described audience members slowly walking out.
"The idea that they said that it was a technical error, when I was maybe [5 meters] away from a potential dangerous substance, that kind of irks me a little bit," Hayden said. "But at no point did I feel an actual threat."
Micaela Baranello, a musicologist at Smith College in Massachusetts, told The Associated Press that some in the audience booed the cancellation, with one man chanting, "I want my money back, I want my money back."
Baranello, who spoke to a reporter by telephone from a train headed back to Massachusetts, said the cancellation of the opera was "too bad, because most of the best music in 'Guillaume Tell' is in Act 4, in my opinion."
The monumental opera had received warm reviews when the Met debuted its new, five-hour-long production 10 days ago. It tells the William Tell fable and, until Saturday, had not been staged at the Met for over 80 years.
The overture to "Guillaume Tell" is known to many in the U.S. as the theme music of the 1950s television series "The Lone Ranger."