Surveillance footage from just outside City Hall reveals that protesters received a shipment of bats to the location just before anti-cops activists clashed with officers on the Brooklyn Bridge, according to Fox News.

A car parked on the street near City Hall unloaded a delivery of 6 bats, according to footage provided by sources.

Police sourced reported that the bats were delivered so that the anti-cop activists could confront a “unity” rally proceeding over the Brooklyn Bridge into Manhattan.

Four police officers were injured, including Chief of Department Terence Monahan — the NYPD’s highest-ranking uniformed officer, and one civilian.

The New York Police Department said confirmed that 37 people were arrested.

More from Fox News:

It’s unclear if the City Hall protesters used the bats in the wild Brooklyn Bridge brawl between opposing protesters. But at least one was recovered after the dust settled, police sources said.

A cane was also used in the melee, with one counter-demonstrator seen on video using the object to whack cops over their head during the melee on the bridge.