Groups of people have been caught mysteriously sneaking in and out of manholes around Brooklyn, stoking fear in locals as an investigation remains ongoing.
Police say that there is no threat to the public, and that the sewer systems have been investigated after the unknown individuals spent hours in the underground tunnels.
Here’s who led the investigation, and what to know about the incidents.
Police investigate mysterious groups entering, leaving Brooklyn manholes
In two separate incidents, surveillance footage has caught groups of people leaving, or entering, manholes in the middle of the night.
The two incidents were reported last week, both in Brooklyn, after police were called for individuals seen going into the manholes. The first group was reported Thursday night, while the other was called in Friday at around 1 a.m.
The Thursday night group was seen leaving about three hours afterward, according to the NYPD, while the second odd circumstance ended after individuals were seen crawling out and leaving in a vehicle more than two and a half hours after.
A law enforcement official said that the NYPD’s main theory is that the trespassers were looking for valuables, according to NBC New York.
But locals expressed concern as the individuals are still unknown, with fears stoked online.
No arrests have been made in both of the incidents, and their investigations remain ongoing, police told USA TODAY.
Who and how officials are investigating the odd incidents
Police said that the NYPD’s Emergency Service Unit, alongside the Department of Environmental Protection’s Bureau of Water and Sewer Operations, scoured the sewer systems for any evidence.
A DEP spokesperson told USA TODAY that “our infrastructure is safe.”
“DEP works closely with our public safety partners to help ensure the safety and security of critical infrastructure throughout New York City,” the official said.
The DEP emphasized the risks— noxious gases, flooding risks, confined spaces, to name a few — of going into the sewer systems, and urged the public to never go inside a pipe, drain, catch basin, manhole, or outfall.
But it isn’t entirely clear what a sewer system investigation would look like, and police did not immediately clarify methods to USA TODAY. New York City’s sewer network is complex, with pipes spanning over 7,400 miles.
This article originally appeared on USA TODAY: Who searched NYC’s sewers after groups vanished into manholes?