Rescue crews battled the clock Tuesday evening in an effort to free a construction worker buried for hours under several feet of dirt and clay.

As of 10:30 p.m., the man had been buried for more than five hours, and hopes were dwindling that he would be found alive.

He was working with a backhoe operator digging a trench at a home construction site near 107th Avenue and 124th Street. The trench collapsed just before 5 p.m. and soon firefighters, paramedics and police converged on the scene.

Desperate hours passed as rescue crews worked to shore up the sides of the trench.

"I'm not going to say he's deceased or anything yet," district fire chief Doug MacDonald said earlier in the evening. "But he's probably 10 feet down, with five or six feet of clay and dirt on top of him."

The backhoe was digging a trench to lay sewer pipes for a new home, MacDonald said.

Firefighters had a technical rescue team on the scene, shoring up the sides so nothing more would collapse.

"It's very unstable and it's hard clay," MacDonald said. "It's just a matter of everyone staying safe."

Asked before 7 p.m. whether the effort was a rescue or a recovery, he said: "It's still a rescue."

But several hours have passed since then and crews have still not reached the man.

Occupational Health and Safety workers were also on scene.