Rejean Aylwin, right, the father of Lucie Aylwin who is presumed trapped in the wreckage of the Algo Centre Mall, walks by a memorial in Elliot Lake, Ont., on Tuesday, June 26, 2012. Rescue workers are attempting a new plan to search for survivors after the mall's roof collapsed Saturday, June 23, 2012. THE CANADIAN PRESS/Chris Young

TORONTO - The heart-breaking decision to suspend rescue operations knowing someone may be trapped in the rubble of a collapsed building — as happened in Elliot Lake, Ont. — is among the hardest for first responders to make, experts said Tuesday.

At the same time, they said, their top priority must be to ensure that rescuers don't add to the tragedy by themselves becoming casualties.

"It's the most difficult thing for a first responder to cease operations because it's not what we do, it's not what we want to do," said Jim Young, who heads up the urban search and rescue task force in Vancouver.

"As clinical or unemotional as that may seem, it absolutely is critical for the incident commander to detach himself emotionally and make decisions based on the facts at hand."

On Monday, responders to the Algo Centre Mall collapse in Elliot Lake suspended operations just hours after reporting signs of life from the rubble.

The decision came after engineers said the already fragile structure was in imminent danger of further collapse, two days after part of the roof came crashing down, killing at least one person.

Bill Neadles of the Toronto-based Heavy Urban Search and Rescue Team said crews were facing the imminent threat of a secondary collapse within the fragile structure.

"The building is ... totally unsafe,'' Neadles said.

The decision to suspend operations outraged members of the community, prompting a demonstration outside the town's city hall.

"We're all devastated, because as far as we're concerned, there's someone alive in there," said one resident, Catherine Timleck-Shaw.

"They should be brought out, and not left in there to die — in our eyes, that's murder."

Some residents suggested calling in mine rescuers given the many mines in the region and the expertise in dealing with people trapped in underground collapses.

Alex Gryska, manager of Ontario Mine Rescue in Sudbury, Ont., said that idea wouldn't fly.

For one thing, he said, the urban search and rescuers have sophisticated technical expertise and specific equipment the mine responders wouldn't have.

At the same time, he said, mine rescue involves the same kind of "delicate" weighing of the risks to emergency responders.

"If this was an underground mine collapse, we would be exercising the same kind of cautions that they would be exercising," Gryska said from Sudbury, Ont.

"When teams are told to proceed, they need to know they're going to do it in safety. The last thing that we'd like to see happen during a rescue event that we have casualties of rescuers."

The situation prompted Premier Dalton McGuinty to convene a telephone conference Monday with the emergency responders to see if there was any way to resume the rescue effort — prompting an announcement the search for survivors would continue, albeit using a different strategy.

In explaining why he had intervened, McGuinty was careful to say he wasn't second-guessing the original decision given the dangers faced by the exhausted and "emotionally distraught" rescuers.

"When you volunteer to participate as part of an emergency team, you never want to leave anybody behind," McGuinty said Tuesday.

"Every cell in your body screams for you to keep going."

The new strategy involves attempting to dismantle the building from the outside, rather than have rescuers go into the rubble itself.

It, too, carries a "real risk" the premier noted, given that the effort could trigger the building's collapse.

"It's not unlike a house of cards," McGuinty said. "I expect them to use good judgment now as they explore this new option."

News from © The Canadian Press, 2012