The bridge structure plunged more than 40 metres, taking with it the lives of 75 workers. ((Courtesy of Mysteries of Canada))

Memorial services were held Wednesdayin Lévis, across the St. Lawrence River from Quebec City, to honour the 75 workers who died there100 years earlier in one of the biggest bridge disasters in history.

Mohawks from the Kahnawake reserve south of Montreal travelled to Lévis to take part in the memorial because 33 of the people who died that day were Mohawks. It was a tragedy that helped create their reputation as high-steel workers.

The Mohawks were among crews of construction workers building the world's longest cantilever bridge, stretching from Quebec City to the south shore where the city of Lévis is now situated.

Just two minutes after their shift ended on Aug. 29, 1907, the whole structure collapsed, plunging them into the St. Lawrence River.

More than two-thirds of the Mohawks who died that day were married, leaving behind 24 widows and dozens of children.

Some of their descendants were among the crowd atthe memorial service.

They dedicated a concrete memorial on the Lévis side of the bridge that will display the names of all ofthe victims.

Another memorial, a steel replica of the bridge, was unveiled in Kahnawake.

The Quebec Bridge was designed to be 853 metres long —including a single span of 548 metres, almost 46 metres above the water —to allow the passage of ocean-going vessels.

Although engineers noticed that the girders had begun shifting on the fateful day, work continued until the whistle sounded at 5:30 p.m. Two minutes later, it was in the river.

The bridge construction was restarted in 1913 and completed in August 1919.