TORONTO (AFP) -- A historic theater in downtown Toronto collapsed while undergoing renovation killing one person, while one person was believed still to be trapped under rubble after two others believed missing were found safe outside the building, authorities here said Monday.

Fire service officials said one adult had been pronounced dead at the scene while 14 victims, including three children, had been transported to different city hospitals.

The tragedy unfolded after a wall at Toronto's vintage Uptown Theater collapsed.

A number of youngsters were next door at the Yorkville English Academy, a school teaching English to adults, when the wall of the theater -- built in 1920 -- collapsed on top of the academy.

"We have transported 10 patients to Toronto General Hospital," fire chief Bill Stewart told AFP, adding that the injured children had been taken to the Hospital for Sick Children, and to St. Michael's Hospital.

"The (rescue) operation seems to be going along quite smoothly," Jim Muscat, a spokesman with the Toronto Police Department, told CNN television.

"There was some type of renovation underway," in the building at the time of the cave-in, Muscat added.

Some of those pulled from the rubble were hurt, but their injuries do "not appear to be life-threatening at his point," Muscat added.

Television news pictures from the scene showed firemen searching through the rubble for other possible survivors after the accident occurred around 10:35 A.M. (1535 GMT).