It's in response to several recent racist incidents in the East Bay city.
The Martinez police chief warned they've got "intelligence that counter-protesters are going to show up to protest the protesters."
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Martinez is at the center of the controversy after racist flyers were circulated in the downtown area according to Together We Stand Revolution. That group has been involved in other large protests in Minneapolis and Charlottesville.
Founder Sevgi Fernandez said it's intended to be peaceful and to call attention to the couple that painted over a Black Lives Matter mural on the street in front of the superior courthouse this week in Martinez.
At another location in town 'white lives matter' was painted on the street.
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She says they are marching to show that "white supremacy and threats are not going to deter us from our goal of racial equality and an end to police brutality."
They've teamed up with Southern Alameda County Resistance.
Spokesperson Michael James said he's gotten several phone calls from white supremacy groups threatening to show up at the march on Sunday and he said they told him they will be carrying weapons. He said his group is providing their own security and will have several medics along with those who participate just in case there is a clash
Martinez Police Chief Marjit Sappal said they intend to keep their police presence low-key enough to provide security but not enough to provoke animosity with the crowd.
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Many downtown businesses aren't taking any chances. Some have already boarded-up windows.
Streets in downtown Martinez will be closed to traffic as of 10 p.m. Saturday night in anticipation of the protest on Sunday.
Organizers intend to rally in front of the County Superior Court building at 4 p.m. and march to the waterfront.