BLOOMINGTON, Minn. (Reuters) - Black Lives Matter held demonstrations in Minnesota and California on Wednesday to protest police killings of unarmed blacks, dubbing the day “Black Xmas” to show it could affect the economy on one of the busiest shopping days of the year.

A protester named Oluchi of Minneapolis speaks to protesters after they shut down the main road to the Minneapolis St. Paul Airport following a short protest at the Mall of America in Bloomington, Minnesota December 23, 2015. REUTERS/Craig Lassig

“Black communities across the United States are taking brave actions to impede the flow of goods and commerce with peaceful protests to call for an immediate overhaul of the justice system,” Black Lives Matter said in a statement posted on Facebook.

“There will be no business as usual until we get accountability for our dead, and justice for the living,” the group added. “Instead of buying gifts to fuel this system, Black Xmas is a day of action.”

The loosely organized movement grew out of protests over police killings of black men in Ferguson, Missouri, New York and other cities.

Citing the lack of an indictment Monday related to the death of Sandra Bland, a black woman who died by hanging in an apparent suicide in her jail cell following a controversial traffic stop, Black Lives Matter on Wednesday called for police accountability and the removal of grand juries in cases involving police shootings.

In Minnesota, a demonstration at the Mall of America by protesters angered by the police killing of an unarmed black man in Minneapolis last month was swiftly broken up.

Black Lives Matter demonstrators camped outside a Minneapolis police station for nearly three weeks after a police officer shot Jamar Clark, 24, on Nov. 15.

The death of Clark, who was unarmed, added fuel to an already heated debate over race and justice following several such killings across the United States in the past year.

“It’s been sleepless nights,” Jamar’s cousin, Alexander Clark, told Reuters at the mall demonstration just before police took him into custody, adding: “We are here for justice for my cousin.” It was not immediately clear whether Clark had been formally arrested.

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After police and mall security dispersed the gathering, the protesters went to the Minneapolis-St. Paul International Airport where they briefly shut down roadways to both terminals, an airport spokesman said.

Security checkpoints in Terminal 2 were briefly shut down to prevent protesters from moving into secure areas of the airport, the second busiest in the Midwest after Chicago’s O’Hare.

Meanwhile, California Highway Patrol said it arrested nine female protesters blocking southbound traffic on the 101 freeway near the San Francisco International Airport on Wednesday.

Images of the demonstrators uploaded to social media showed them holding a sign demanding justice for Mario Woods, a black man suspected of a San Francisco stabbing, who police shot dead.

Earlier, about 100 people had started to gather at the Minnesota mall, one of the largest in North America, despite a judge’s warning that its owners could legally block the protest.

Police and mall security quickly moved in, warning that any who did not leave would be arrested for violating mall policy against demonstrations and alerting shoppers that that area of the mall was on lockdown. Some stores closed for about an hour.

Mall officials said Bloomington police arrested four people.

Black Lives Matter Minneapolis officials had promised to assemble “restraining order or not” and said in a Facebook post late Tuesday, “What happens next will tell us volumes about who we are as a society.”

Just before last Christmas, more than 1,500 Black Lives Matter protesters shut down part of the same mall as they demonstrated against grand jury decisions not to charge police officers in the killings in Ferguson and New York.

The night before this year’s Macy’s Thanksgiving Day parade in New York, members of the group marched through Macy’s Herald Square flagship store to show solidarity with the Minneapolis chapter.