The Oakland Police Department (OPD) estimated 7,000 demonstrators at the height of the peaceful demonstrations that took place throughout the city on Wednesday. But by midnight, OPD came out in riot gear again and began firing tear gas and rubber bullets at a small group of protestors. Now, protesters and police officers alike are turning against Mayor Jean Quan.

Occupy Oakland leaders staged several peaceful marches throughout the day. That includes yesterday evening’s march that shut down the Port of Oakland, the nation’s fifth busiest port, for two shifts. Hundreds of workers, including 16 percent of Oakland Unified school teachers and other city employees, participated in the general strike.

Shortly after midnight a group that had taken over a foreclosed building that used to house a service agency began to start fires, and that reportedly the breaking point for the police department.

The clashes followed soon after. The Bay Citizen was at the scene and provides details:

…around midnight, officers fired tear gas at protesters who had taken over a vacant building and set makeshift barricades ablaze near 16th Street and Broadway.

As police were approaching the barricades, Oakland’s mayor, Jean Quan, was sending out tweets urging protesters to contact her office.

But within three minutes, officers began firing tear gas at the demonstrators, who had been throwing firecrackers and bottles at police, according to witnesses and news reports.

It’s unclear whether the police department contacted the mayor before firing tear gas, but what’s clear is that there is tension and disagreement within both the Mayor’s office and the OPD.

On Monday, the Oakland Police Officer’s Association that represents the city’s 645 police officers wrote a scathing open letter to Oakland residents accusing the city’s first Asian-American mayor of not making "sound decisions" and leaving everyone, including the cops, confused.

"On Tuesday, October 25th, we were ordered by Mayor Quan to clear out the encampments at Frank Ogawa Plaza and to keep protesters out of the Plaza," the open letter reads. "We performed the job that the Mayor’s Administration asked us to do, being fully aware that past protests in Oakland have resulted in rioting, violence and destruction of property."

"Then, on Wednesday, October 26th, the Mayor allowed protesters back in – to camp out at the very place they were evacuated from the day before."

The back and forth between the police department and the Mayor’s office and the rising number of incidents in which police use excessive force may ultimately leave the police department in federal receivership.

In a Colorlines.com story published after the October 25th incidents, Ali Winston provided some context and history of Oakland police using excessive force:

Over 2,500 people have been arrested across the United States as the Occupy Wall Street movement has spread from its genesis in Lower Manhattan to over 1,000 American cities and municipalities, where occupiers struggle with city officials for control of public spaces. But the previous scenes of mass arrests in places like Chicago’s Grant Park and on the Brooklyn Bridge paled in comparison with the chaos that broke out in Oakland this week.

The Occupy Oakland movement has run up against one of the country’s most troubled law enforcement agencies, and a community that has grown impatient waiting for its reform. The projectiles police fired in clashes with protesters seriously injured a young Iraq war vet, Scott Olsen, which helped draw national outrage over the scale of force that police used. That sort of violent over-reaction and the tactics associated with it are, however, all too familiar in Oakland, where police have repeatedly responded to public protest with violence and have faced intense scrutiny for shooting unarmed suspects in black neighborhoods, in some cases fatally.