Philadelphia Orchestra concertgoers experienced a rare interruption Friday afternoon when a fire alarm in the Kimmel Center sent audience and musicians out of the complex.

No fire was reported after an alarm was triggered at 2:29 in the Perelman Theater, which was also evacuated, said Kimmel Center spokeswoman Leslie Patterson-Tyler. The Philadelphia Fire Department conducted an investigation, and within 40 minutes the Kimmel was deemed safe and visitors were allowed to return.

"We are investigating what may have triggered the alarm," said Patterson-Tyler.

The orchestra's matinee resumed after the interruption, which also resulted in the evacuation of the audience for Paper Planet: Polyglot Theatre, a show for children in the Hamilton Garden, part of the Philadelphia International Festival of the Arts.

The alarm sounded while the orchestra was playing Ginastera's Variaciones concertantes in a program that concluded with Stravinsky's The Rite of Spring - a curious echo of an event in 2002, when a rehearsal of The Rite of Spring in Verizon Hall was interrupted not only by a fire alarm, but also by the sprinkler system.

Valuable stringed instruments were soaked in the 2002 deluge, as was a Steinway grand. Conductor Christoph Eschenbach dubbed it "the Rite of the Sprinkler."

The hall's sprinkler system was not activated Friday afternoon, said orchestra vice president for artistic planning Jeremy Rothman.

- Peter Dobrin