New York City police made multiple arrests Friday at another anti-ICE protest outside 26 Federal Plaza. 

The building in Lower Manhattan houses a U.S. Immigration and Customs Enforcement processing center, where protesters allege immigrants are being detained in deplorable conditions. 

Video shows protesters in the street holding a banner reading "Free Them All" and signs that say "Rise Up Against Cruelty," among other slogans

The NYPD said 15 people were arrested at the protest, but did not say what they were charged with. 

The Department of Homeland Security maintains 26 Federal Plaza is not a detention center and says allegations of overcrowding or poor conditions are "categorically false." 

"It is a processing center where illegal aliens are briefly processed to be transferred to an ICE detention facility," DHS Assistant Secretary Tricia McLaughlin said in a statement to CBS News New York. "All detainees are provided with proper meals, medical treatment, and have opportunities to communicate with their family members and lawyers. As we arrest and remove criminal illegal aliens and public safety threats from the U.S., ICE has worked diligently to obtain greater necessary detention space while avoiding overcrowding." 

A wave of immigration protests in New York City

The wave of rallies outside 26 Federal Plaza has been ongoing for months, but it picked up in July after the New York Immigration Coalition released video appearing to show inside the 10th floor processing center. 

In the video, men are seen in a room with no furniture, many appear to be laying or sitting on towels and foil blankets on the floor, and one of two toilets behind half walls in the back appears to be covered with a foil blanket. The person taking the video says, "Look how they have us here like dogs."

CBS News New York verified the video after its release, but it is unclear when it was taken.

DHS also denied the allegations when the video came out.