At least one person is feared dead and another trapped inside the rubble of a roof collapse at mall in northern Ontario, authorities said Sunday.

More than 24 hours after the collapse, rescue workers have been unable to reach the victims because the structure is too unstable. But images taken with the camera show a hand and foot in the dusty debris, said Ontario Provincial Police Insp. Percy Jollymore.

Fire officials heard tapping Sunday morning in another part of the rubble, but nothing had been heard for hours. They said they also tried to reach that person by drilling through a wall, but found the structure too unsafe to risk entering far enough inside.

"Some of our search members this morning heard a couple of taps," said Bill Needles, a spokesman from the Heavy Urban Search and Rescue team which travelled from Toronto. "They called for a quick silence on the site and there was a couple more taps. That was an indication to us that we were dealing with a rescue."