They warned it was going to happen, and about 150 people followed through on that warning.
The protestors from the group, Extinction Rebellion, blocked the Bloor Viaduct to vehicular, pedestrian and cyclist traffic.
They demanded the government make real change when it comes to climate change.
The protestors are blocked all traffic at Broadview to the east and Castle Frank in the west.
Toronto is not the only target, with protests being held in other cities across the country, like Halifax, Vancouver and Victoria.
The group was founded in the UK, and this protest is part of a movement across the world called Global Rebellion. Those protests are all expected to be non-voiolent and protestors say they are designed to draw the attention of the world of the urgency surrounding climate change.
Some of the protestors in Toronto were on the bridge, doing yoga and meditating, while others were pacing, carrying placards.
Police eventually told the crowd to disperse, and most did, but a handful of protestors remained. About a dozen were removed by police, and arrested.