Noah Berger/AP

Police have used tear gas and “flash bang” grenades on a large crowd of demonstrators that lit a massive bonfire in the streets of downtown Oakland, Calif.,  in a conflict following a day of action that saw the city’s port closed after demonstrators. blocked it

Dozens of police in riot gear advanced on protesters who had pushed together several large metal and plastic trash bins to start a fire that reached 15 feet in the air, according to The Associated Press. Police reportedly warned protesters to clear out before firing several rounds of tear gas and “flash bang” grenades.

Several protesters, many of whom wore gas masks, chanted “We Are Scott Olson” as the police fired at them early Wednesday. Olson is the Iraq War veteran who suffered a fractured skull last month after he was  hit in the head by a projectile during a conflict with police.

The conflict came hours after thousands of Occupy Oakland protesters marched on the Port of Oakland, disrupting operations at the nation’s fifth largest port and causing all maritime operations in the city to be shut down.

Officials at the Port of Oakland said Wednesday that they hope to resume normal operations in the morning after protesters marched through the city all day and into the night on a “general strike” that saw banks and stores picketed and disrupted the flow of traffic.

Demonstrators began marching to the port at 4 p.m. Wednesday, and by 5 p.m. all work had been halted at the port. A message on the website OccupyOakland.org said that the goal was “to stand in solidarity with the longshore workers and shut down the evening shift of the port.”

Omar Benjamin, the director of the Port of Oakland, confirmed the closing of the port at a late-evening news conference.

“Maritime operations remain effectively shut down. And the port is working to ensure that all workers in the harbor area can get home safely. … It is our hope that the work day can resume tomorrow and port workers will be allowed to get to their jobs without incident,” Benjamin said.

“Continued missed shifts represent economic hardship for maritime workers, truckers and their families as well as lost jobs and lost tax revenue for our region,” he added.

Wednesday’s march through Oakland was largely peaceful according to Oakland’s interim police chief Howard Jordan.

“There’ve been no arrests, there have been no injuries. Earlier today at about 7:46 we received a call of a pedestrian that was struck by a vehicle,” Jordan said late Wednesday.

Several banks were vandalized and a dozen windows were shattered at the Wells Fargo branch, while an area of Whole Foods was vandalized after rumors spread that employees who participated in the strike would be fired, according to ABC News affiliate KGO.

Conflict among  protesters arose as some scrubbed graffiti from a branch of Wells Fargo bank and a group of protesters attempted to stop another from vandalizing a Whole Foods, KGO reported. A police spokesperson said that five businesses were vandalized throughout the day.

Late Wednesday Oakland Mayor Jean Quan confirmed that the protesters were leaving the city’s port.

“Literally thousands of people have demonstrated today in Oakland primarily peacefully. We are disappointed that a small group created some vandalism,” she said. “It looks like this was a good day for demonstrators and for the 99 percent movement.”

Quan’s support of the protests has created controversy amongst city workers. After ordering officers to clear protesters last week, Quan now supports the movement and gave city workers other than police the day off to join the work stoppage.

In an open letter from the police union, officers accused her of sending mixed messages.

“As your police officers, we are confused,” the letter read. “Is it the city’s intention to have city employees on both sides of a skirmish line?”

The Occupy Oakland has quickly become one of the largest movements in the country after the Occupy Wall Street movement began in mid-September. The movement in Oakland became a flashpoint last week when police used teargas to disperse crowds and Iraq War veteran Scott Owen was hospitalized with a critical skull fracture after he was hit with a projectile during a clash with police.