Staff members and a Moscow fire department official said nobody was injured in the blaze at the Musical Theater of Stanislavsky and Nemirovich-Danchenko, across the street from the Russian parliament's upper house. The fire was put out after four hours.
Vasily Vasilyev, an aide to the theater's director, said the fire started just before 7 p.m. Speaking on TVS television, a woman who had been inside the theater said the evacuation order came after a bell signaled that the performance was about to start.
More than 1,000 spectators and 250 actors and staff were evacuated, Vasilyev said. He said no one panicked.
About three hours after the blaze broke out, several fire engines surrounded the theater, and ladders lay against the walls of the five-story building. The sky was smoky, and musicians stood nearby waiting for word of instruments and other possessions they left in the theater.
The official said the main hall of the theater and its stage were not burned, but the extent of the damage elsewhere was unclear.
Vasilyev said the fire damaged service areas at the back of the theater. A producer at the theater who gave only his first name, Andrei, said the fire started on the fourth floor, which was wrecked.
He said the main auditorium was dark and there was water in the orchestra pit.
News reports quoted police officials as saying the fire started in or near the attic and part of a ceiling between the attic and the third floor collapsed.
Moscow police spokesman Valery Gribakin said the cause was not clear but it might have been an electrical short circuit.
