NYPD investigating after surveillance video captures group entering sewers through manholes

Police in New York City are investigating after several people were caught on surveillance video this week going into the sewer via a manhole and emerging hours later.

"Earlier today, authorities conducted a thorough investigation following reports of unauthorized individuals inside the sewer system on McDonald Avenue," the NYPD said on social media. "The NYPD and other agencies have completed their sweep, confirming the area is safe and free of hazards."

The people were seen entering the manhole around 11 p.m. on Thursday in the Flatbush neighborhood in Brooklyn and reemerging around 2 a.m. on Friday, according to PIX 11-TV.

Another group was seen going into a manhole on another street and coming out around the same hours, the station reported, citing police.

250 MILLION GALLONS OF SEWAGE HAVE CONTAMINATED THE POTOMAC RIVER IN 'HISTORIC' SPILL

The police don’t yet know who the sewer explorers were or what they were up to.

The New York City Department of Environmental Protection also did its own inspection, telling Fox News Digital: "DEP has inspected the sewer infrastructure at this location and found no damage to the system."

The spokesperson warned, "Entering the sewer system is both illegal and extremely dangerous. Sewers can contain numerous hazards, including noxious and potentially deadly gases, unstable surfaces, flooding risks, and confined spaces. For these reasons, members of the public should never enter a pipe, drain, catch basin, manhole, or outfall."

Fox News Digital has reached out to the NYPD for comment.