An ambulance has arrived and crane work halted temporarily before resuming this morning at the scene of a partially collapsed shopping mall in Elliot Lake, Ont., where crews using sophisticated equipment were searching overnight and into the morning for any survivors of the weekend tragedy.

CBC's Natalie Kalata reported that Gary Gendron, whose fiancée, Lucie Aylwin, is believed to be in the ruins of Algo Centre Mall, told her he has received "good signs" from officials.

"After nearly four days, the news that there are good signs is rather remarkable," Kalata said.

"We're expecting more information, but we can tell you that an ambulance has gone again back into the scene here ... where we believe people are."

At least one person has been confirmed dead after the roof-top parking lot of the mall caved in Saturday afternoon, sending metal and concrete debris crashing through two floors of the building in Elliot Lake, 150 kilometres west of Sudbury.

Another 12 people remain unaccounted for, down from the 30 officials earlier estimated were missing.

Dan Hefkey, commissioner of community safety for Ontario, said Wednesday morning that using the robotic arm on equipment from a Toronto construction firm, crews were able to move a massive section of an escalator and stairs that had prevented rescue workers from entering the mall.

He also said a robot was able to examine the area and determine that no other debris had fallen as a result of the work.

However, Hefkey said more material needed to be removed before a structural engineer could assess whether it is safe to send in a canine unit to begin the search for "signs of life" around the area where victims are believed to be.

Hefkey said it was unclear when search crews could enter the site.

“I cannot give you a timeline; it’s going as quickly as it can, as safely as it can,” he said.

However, the likelihood of finding survivors is becoming increasingly slim, officials warned.

Bill Neadles from the Toronto-based Heavy Urban Search And Rescue Team said no one has detected signs of life since Monday morning, when officials said it appeared that at least one person was alive in the rubble.

"Based on the information that we supplied him, our doctor was of the opinion that it was a very slim ability for that person to remain alive," said Neadles on Tuesday.

The controlled demolition of the structure is part of a renewed bid to search for any survivors after rescue efforts were halted for several hours on Monday due to safety concerns, including the threat of another collapse.

Working from the outside of the building, crews began dismantling part of the mall's facade Tuesday. Dozens of people camped in front of the mall at night, anxiously awaiting information on those trapped inside.

Could cause further harm

The decision to stop rescue operations prompted outrage from many residents. They erupted in cheers as work resumed.

Although many appeared happy, others expressed concern that removing chunks of the building with heavy machinery could cause further harm to anyone alive inside.

"It's heartbreaking, just knowing the instability of the building, that it might be causing more destruction on the inside," said Penny Craig.

At least one Canadian Forces member is due to arrive in Elliot Lake on Wednesday to help with communications between Emergency Management Ontario, the municipality and, if required, the Armed Forces.

Ontario Provincial Police Insp. Percy Jollymore said officers have had a difficult time determining how many people may be trapped in the debris, as the number of missing changes as people make contact with loved ones.

"We are getting calls basically from all around Canada. We're really looking for people who could be in the mall," Jollymore said. "We still cannot determine how many people are there. We just don't know."

Gendron told CBC News on Tuesday that Aylwin was working in the mall during the collapse.

A woman who only provided her first name told CBC News she saw Aylwin during the cave-in.

"She's just there and it's like she just went right through the floor. I didn't see her," Lyn said. "One second she's in front of me, next minute, she's gone. I don't know what happened. It was so fast, and I can't get it out of my mind."

A family friend of one of the other missing women, Doloris Perizzolo, said life has changed for everybody in Elliot Lake.

"After 2:19 on June 23, things changed here, it was not the same," said Adam Ayotte.

With files from The Canadian Press