20 arrested at megamall

• Police arrest at least 20 demonstrators, CNN affiliate reports


• Mall management asks organizers not to hold the protests on its private property


• Hundreds chant, hold up their hands and lie down to play dead


• Mall of America says it's the nation's largest

(CNN) -- A choir of protests echoed through the country's quintessential megamall, when a few hundred demonstrators from Black Lives Matter raised their voices at the Mall of America.

They held the protest Saturday against the Bloomington, Minnesota, mall's wishes, and were met by police who made at least 20 arrests, CNN affiliate KARE reported.

"We are extremely disappointed that organizers of Black Lives Matter protest chose to ignore our stated policy and repeated reminders that political protests and demonstrations are not allowed on Mall of America property," AoM's said in a statement.

The mall bills itself as the nation's largest with more than 500 businesses. It is big enough to hold seven Yankee Stadiums, its management boasts.

It is home to an indoor roller coaster, the Sea Life Aquarium, and about a dozen more attractions, but on Saturday amusement was drowned out by echoes of "black lives matter" and "no justice, no peace."

Marchers raised their hands in the air and lay down to play dead -- simulating the deaths of young black men Michael Brown of Ferguson, Missouri, and Eric Garner, of New York, in confrontations with police.

As protesters unfurled banners of "hands up, don't shoot," the mall answered with a video wall message in all caps reading:

"This demonstration is not authorized and is in clear violation of Mall of America policy. We expect all participants to disperse at this time. Those who continue to demonstrate will be subject to arrest."

Management shut down the stores on one side of the mall.

Officers called out to the crowd to leave, police spokesman Mark Stehlik told KARE. But officers seemed patient, giving protesters multiple chances to comply.

"They could have arrested me; they could have escorted me. They just asked me nicely to leave, and I did," said Michael McDowell, one of the protest organizers.

Police then arrested some who were less willing to leave on their own, KARE reported.

Prosecutors plan to throw the book at them.

"They knowingly broke the law. They were involved in a situation that was very potentially dangerous," city prosecutor Sandra Johnson said.

CNN's Janet DiGiacomo contributed to this report.