A rural municipality in east-central Saskatchewan is promising an investigation into the collapse of a bridge that was opened just hours earlier.

The incident took place late Friday afternoon at the site of the Dyck Memorial Bridge in the RM of Clayton.

No one was on the bridge at the time and nobody was injured.

"I can't even explain what I felt," RM administrator Kelly Rea said.

"I was on my way out of town. I turned around. I came right back. I went straight to the site. I couldn't believe it. And all I could think of was, 'I hope nobody got hurt' because I didn't have that information."

Work on the new bridge over the Swan River began in early August to replace an older bridge that Rea said was failing.

A statement the municipality put on its website and Facebook page said "the bridge was built to Canadian Bridge Standards and unfortunately something under the riverbed failed, that could not have been anticipated. This caused the pier to sink and the middle span to fall off the pier cap and into the river."

According to Rea, work on the new bridge was completed the day before Friday's collapse.

"They built the bridge. It was nice and flat. It was perfect. And the next day, the piers sank."

The bridge before it collapsed. (Photo submitted by Duane Hicks.)

The RM's statement indicated the engineer in charge of the project would begin repairs immediately. It also said the work was covered under the warranty of the original build.

In the meantime, Rea said the municipality is trying to get a company to "come out and do some testing."

"We don't know what happened," she said.

"We can't place fault yet because we don't know what happened. That's why we need to look into it."

She said the RM had six companies submit bids for the original project. However, it wasn't the lowest bid that got the job, but the "best fit."

Construction and design were handled by Can-Struct Systems and Inertia Solutions, which have the same owner.

"We chose this tender because they gave us the most for the dollar value," she said. "And we were confident we would have a good product when we were finished."

Rea said ensuring this doesn't happen again is now the RM's main priority.

"We will fix this," she said.

She couldn't say when the equipment would arrive to dismantle the bridge.

With files from CBC's Geoff Leo