24News.ca

A single lane of traffic has reopened as crews work to fully repair a damaged bridge on the Trans-Canada Highway, which the Ontario premier described as a "lifeline" to the area.

The Nipigon River Bridge is the only major thoroughfare connecting northwestern Ontario to the rest of the province.

""It is the lifeline in terms of product and transportation in northwestern Ontario and as people have said, it connects the east to the west and there is only that one route," Ontario Premier Kathleen Wynne told reporters in Toronto on Monday.

On Sunday evening, the bridge was closed after part of the steel decking separated from the rest of the structure. The cause of the damage is not yet known.

"There will be many questions that will be asked about why this has happened. I don't have the answers at this point," Wynne said.

"We'll get to the bottom of it, we'll figure out what it was and we'll make sure that it's rectified."

By Monday morning, crews were able to open one lane for cars and regular weight transport trucks, according to a statement from the Ministry of Transportation. However, it is not yet known when oversized trucks will be able to use the bridge, nor is it known when the rest of the bridge will reopen.

The statement said Ontario Northern Development and Mines Minister Michael Gravelle would visit the site to assess the damage on Monday morning.