By Colin Perkel, The Canadian Press

Heavy equipment was brought in Saturday in an effort to recover the body of a worker trapped in the rubble of a partial collapse of a building under construction in London, Ont.

The incident on Friday killed two people and injured five others, city officials said. One person killed had earlier been taken from the scene but the other remained trapped.

Officials said efforts to get to the second victim — who was confirmed dead — were delayed out of fear the unstable structure could collapse further.

The provincial Heavy Urban Search and Rescue team was called in to help but the recovery could take "some time," officials said.

It’s not clear what caused the mishap and an investigation was underway, the city said.

Of the five injured, four needed hospital treatment, London Health Sciences Centre said, two were in serious condition and the other two in fair condition. A fifth worker was only slightly hurt.

Mayor Ed Holder expressed his condolences to relatives of the victims and thanked first responders for their response to the "tragic incident."

"The community joins me in expressing our deepest condolences to the families of the two people who lost their lives," Holder said in a statement. "My thanks go to all of our first responders and to our emergency management team for their swift action." .

The victims were all workers on site when a wall caved in just before noon on Friday.

Two investigators from the Ontario Ministry of Labour and an engineer were called to the site managed by Brock Developments. The address, listed as a low−rise "premium" apartment building called Nest on Wonderland, was scheduled to be finished by next summer.

Michelle Doornbosch, president of Nest on Wonderland, said the company was co−operating with regulatory authorities as they carried out their investigation.

"We are devastated by this incident, and our thoughts remain with the affected workers, their families, friends and co−workers," Doornbosch said in an email.

The London Health Sciences Centre declared a "Code Orange" in response to the incident but later called that off. It also said its doctors had gone to the scene to help as they could.

The hospital said it had received five patients, including one of the fatalities. No further information would be provided on the surviving patients, it said.

Photo by Nicole Thompson, The Canadian Press

(C) The Canadian Press