Stranded communters had to wait as long as an hour for northbound shuttle buses at the corner of Bloor Street and Yonge Street on Wednesday evening. (Robin Rowland/CBC)

Subway service has resumed between Eglinton and Bloor stations on Toronto's north-south Yonge line following a closure that lasted around five hours and delayed thousands of commuters.

The Toronto Transit Commission closed the subway line between the two stations at around 3 p.m. ET.

Bridge repairs above a subway tunnel just south of the St. Clair station may have compromised the tunnel's integrity, according to the TTC.

A contractor not associated with the transit authority was "cutting about an 18-inch-wide [46-cm-wide] trench — the kind of trench you see for laying cables and whatnot — not realizing that below that roadway was a subway tunnel," TTC spokesman Brad Ross told CBC News.

The TTC had "real concerns" the weakened portion could collapse into the tunnel, Ross said.

But at 8:25 p.m. ET, the TTC issued a release stating "full subway service has resumed on the Yonge-University-Spadina line."

Earlier in the day, the TTC indicated that portion of the subway would be closed overnight, and couldn't even guarantee the Yonge line would be fully running by Thursday morning.

Ross had said that work on ensuring the tunnel was safe was "going to take all night."

During Wednesday evening's rush hour, commuters had no access to the subway at Davisville, St. Clair, Summerhill and Rosedale subway stations. More than 50 shuttle buses were running between Eglinton and Bloor.

Thousands of people who would ordinarily have been riding the subway on weekday evenings spilled onto the intersection of Yonge and Bloor to walk or line up for one of the shuttles.

The CBC's Lorenda Reddekopp, reporting from outside Rosedale subway station at around 6:45 p.m. ET, said shuttle buses heading both northbound and southbound were packed with people.