I'm afraid because there are some people there that I know. I want news about them," Serra said.

Police dogs sniffed for signs of one person authorities believed was trapped in the rubble. Dogs and firefighters also were digging through debris to reach a car crushed in an alley.

"It's going to take an immense amount of time to get into the rubble and shore it up," Toronto Fire Chief Bill Stewart said, adding that five construction workers in the theater were among the wounded.

Police Chief Julian Fantino said "the situation is precarious at best and dangerous for the rescue operation people."

He said the busy nature of the site's downtown location made it difficult to determine exactly how many people may have been caught in the collapse.

"My daughter called me right after it happened and said the roof had collapsed," said Helen Wanger, a parent of an injured student who was taken to a hospital.

The Uptown Theater, which opened in 1920 as a movie theater and a stage venue, is considered a historic site and was the subject of an unsuccessful campaign to stop its demolition. In May, the company Famous Players sold the building for $7.5 million to Piagga Ltd., a developer with plans to build a 50-story apartment building on the site.

Toronto city councilor Kyle Rae, who represents the ward where the theater is located, told reporters he received a telephone call Sunday from a Piagga employee expressing "concerns over safety problems." Rae did not elaborate. The Uptown was one of three theaters that Famous Players decided to shut down rather than follow government directives to make them wheelchair accessible.

The Uptown Theater, which opened in 1920 as a movie theater and a stage venue, is considered a historic site and was the subject of an unsuccessful campaign to stop its demolition. In May, the company Famous Players sold the building for $7.5 million to Piagga Ltd., a developer with plans to build a 50-story apartment building on the site.

Toronto city councilor Kyle Rae, who represents the ward where the theater is located, told reporters he received a telephone call Sunday from a Piagga employee expressing "concerns over safety problems." Rae did not elaborate. The Uptown was one of three theaters that Famous Players decided to shut down rather than follow government directives to make them wheelchair accessible.