A construction worker who was pinned under a cement slab at a site in the Sandy Hill area of Ottawa has died of his injuries after being transported to hospital Wednesday without vital signs.

Paramedics got the call to a house on Marlborough Avenue just after 1:30 p.m. and found two men trapped under a piece of concrete foundation that had collapsed into a cold-storage room below.

Both men were working on the porch of the home before they plunged four metres.

"When [the foundation] basically gave way, two of the workers went down into the hole, and the concrete slab followed suit and landed on top of them," said Marc Messier, Ottawa Fire spokesman. "One of the workers was able to get out on arrival with the assistance of firefigthers and paramedics."

But a 48-year-old man was still trapped beneath the slab. Although he was conscious and able to speak, he lost his vital signs once rescue teams removed the obstruction, said Ottawa Paramedic Services team leader Jean Hamel.

"On arrival, he was obviously making noise. He was alive," Hamel said. "Once they extricated him out, there was no pulse on the patient."

The other worker on the scene, who is 36 years old, was treated for a fractured ankle, paramedics said.

Police have not released the identity of the victim who died, and officials from the Minister of Labour were still on the scene investigating what caused the accident. As is standard practice with construction accidents, an inquest will be called into the incident.

In the meantime, police closed Marlborough Avenue between Laurier Avenue and Osgoode Street.