A group of people seen climbing out of a manhole near Penn Station has raised questions about what happened below the street, with the NYPD investigating how they got into the sewer system.

The video was recorded early Tuesday near West 32nd Street and Seventh Avenue, according to police. It shows several people emerging from a manhole across from Penn Station.

“Where are they coming from? What are they doing down there?” one man outside Penn Station said.

The NYPD said it is investigating the incident. Police have not announced any arrests and have not said whether the people seen in the video have been identified.

The incident is not the first time people have been captured on video inside New York City’s underground infrastructure. Earlier this year, a video in Queens showed another group underground. Police described those people as migrants who appeared to be scavenging.

Police have not said the two incidents are connected.

“I just feel like it’s not safe because if people have access to it, who knows what else is going on down there?” Manhattan resident Dylon Vanhorne said.

The unusual activity has also raised concerns about security beneath the city’s streets.

“There’s obviously serious security concerns,” Brooklyn resident Elihu Conant-Haqut said.

While police have not identified any specific threats, retired FBI Special Agent Richard Kolko said the circumstances warrant a closer look.

“We’ll have to figure out what they’re doing because it’s New York City, and there’s always concern that if somebody has some ill intent,” Kolko said.

Kolko said investigators will want to determine who the people are, why they were underground and whether they have entered the sewer system before.

He also urged New Yorkers to report suspicious activity.

“If you see something, say something,” Kolko said.

The Department of Environmental Protection said it inspected the sewer near the location and found the infrastructure to be safe.

But the agency warned that entering the sewer system is illegal and extremely dangerous. Potential hazards include deadly gases, flooding and confined spaces.

The NYPD said it is reviewing security camera footage from nearby buildings as the investigation continues.