Police in Massachusetts reportedly arrested 12 pro-immigration protesters Thursday after hundreds of demonstrators marched through the Boston area, blocking rush-hour traffic.

The group, arrested for trespassing at the Amazon building in nearby Cambridge, across the Charles River via the Longfellow Bridge, were advocating for private businesses to stop cooperating with U.S. Immigration and Customs Enforcement (ICE), Cambridge police said, according to The Hill.

The unscheduled route frustrated passengers and police. “It’s rush hour, there’s only one way (on the bridge). Take some other way around,” a man said to WBZ-TV in Boston. The protesters reportedly refused to tell police their planned route.

“It’s rush hour, there’s only one way (on the bridge). Take some other way around.” — Boston-area rush-hour commuter

PROTESTERS IN NYC RIP ICE, TRUMP'S IMMIGRATION POLICIES; COUNTER-PROTESTERS SAY DEMS TO BLAME FOR BORDER CRISIS

The organizers, "Never Again Action: Jews Against ICE," posted on Facebook they were specifically protesting Amazon’s contracts with ICE and the company’s reported attempts to sell its facial recognition technology to the agency, The Hill reported.

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Eighteen people were arrested at a similar "Never Again" protest in July.