Tensions ran high Monday morning as climate action protesters shut down traffic on the Walterdale Bridge, making all three northbound lanes impassable to commuters during rush hour traffic.

Extinction Rebellion, the group behind the hour-long protest, began blocking traffic at 7 a.m.

Nine protesters with hands linked blocked drivers from crossing the bridge. One of them was Michael Kalmanovitch, the Green Party candidate for Edmonton Strathcona in this month's federal election.

A line of waiting vehicles immediately began to snake up the length of Walterdale Hill and Queen Elizabeth Park Road.

Organizers, who planned on waving banners and handing out cookies to passing motorists, described the protest as peaceful but some commuters clashed with demonstrators.

'Fists flying'

A revving motorcycle could be seen driving around the line of protesters. Another driver attempted to get around the demonstrators while repeatedly honking his horn. Bicycles placed on the road by protesters as a barrier were thrown to the sidewalk.

Many drivers got out of their vehicles to scream and curse at the demonstrators.

Commuter, Jack Haworth, who was stuck in the queue for about an hour, said the demonstrators were not winning any support.

"I think there are definitely channels that would be more suited to doing this and not interrupting people's lives," Haworth said.

"It's frustrating. I think everyone here has a sensitivity to climate but there are definitely better ways to channel that … rather than punishing people for trying to get work in the morning. It's ridiculous."

Some drivers became irate as climate action protectors blocked the Walterdale Bridge during rush hour Monday morning. (Lydia Neufeld/CBC)

Edmonton police were on scene diverting traffic from the area. A spokesperson said officers responded to reports of fighting on the bridge.

"I think there were some very ticked off commuters to say the very least," Staff Sgt. Neil Thompson said in an interview with CBC News.

"I think there might have been some fists flying but I think that stopped fairly quickly."

We said, 'Please'

The bridge was cleared around 8 a.m. after police had a discussion with the demonstrators, Thompson said.

"The bridge is clear. We said, 'Please.'"

Protesters hoped to block traffic until 9 a.m., but agreed to end the blockade at 8:15 a.m. after negotiations with police "and they honoured their word" by leaving a few minutes earlier, Thompson said.

After the protest, police issued a news release saying officers "moved first to maintain public order as angry drivers were approaching the protesters."

Police formed a line between protesters and commuters, while an officer conducted negotiations.

Police warned protesters they could be arrested. No charges were laid at the scene, but the protest is under investigation and charges could be laid in the future, the release said.

"In Canada, all people have the right to gather peacefully. There are, however, limitations on peaceful assembly contained in various sections of the Criminal Code.

"Police wish to thank the many citizens who were inconvenienced this morning in traffic for their patience."

A climate protest on the Walterdale Bridge exasperates commuters. 1:22

'We did our part'

Demonstrator Devin Radcliffe said he feared for his safety at times.

"There was a moment when the man who was driving his car toward us. I thought he wasn't going to stop but you have to rely on the goodness of other people."

Radcliffe said in spite the angry reaction from some commuters, the protest was a success.

"One hundred per cent. We did our part today," he said.

"I think you need to have a wide variety of tactics to achieve success especially with an issue so complex as climate change."

10 protestors blocking access across Walterdale br <a href="https://twitter.com/hashtag/yeg?src=hash&ref_src=twsrc%5Etfw">#yeg</a> Man laying on his horn trying to get them to move <a href="https://t.co/nT4AD2wuYK">pic.twitter.com/nT4AD2wuYK</a> —@LydiaNeufeldCBC

The protest was part of the #BridgeOut campaign, a series of similar actions taking place across North America and Europe.

Extinction Rebellion targeted Toronto's Bloor Viaduct and the MacDonald Bridge in Halifax, backing up commuter traffic as thousands of people seek alternate routes to work. Demonstrators also planned similar protests in London, Paris, Berlin and New York.

"By engaging in civil disobedience, Extinction Rebellion Canada hopes to pressure elected officials to enact legally-binding policies to reduce Canada's carbon emissions to net-zero by 2025," reads a news release from Extinction Rebellion.

"This demand aligns with what the world's best climate scientists tell us is needed to prevent runaway global warming."

The blockade lasted about an hour Monday morning before police intervened. (Dave Bajer/CBC)

with files from Lydia Neufeld