Three unidentified people were seen emerging from a manhole in New York City’s Upper East Side neighborhood early Wednesday before fleeing the area, police said, in an incident that comes as many world leaders have gathered in the city for the United Nations general assembly.

The incident is the latest in a series of similar cases involving people entering or emerging from New York City’s sewer network in recent months that have gone viral online.

A spokesperson for the New York City police department (NYPD) said in a statement that the incident appeared to fit the “same criteria” as several of the similar episodes reported in recent months of “individuals going into the sewer system to look for valuables and other scrap metal after a storm”.

But, the police said that “out of an abundance of caution given the UN General Assembly and the sensitivity of the location, the NYPD is conducting additional security sweeps with our federal partners”.

The spokesperson said on Wednesday that the police department has a “robust response to these incidents which were deployed overnight and additional measures today”.

There is currently no indication that the incident was connected to the UN general assembly.

According to the NYPD, officers responded to a 911 call reporting a possible crime on the corner of east 61st street and Park avenue, at around 4.35am on Wednesday morning. When officers arrived, the NYPD said that they were told that “three unidentified individuals” had exited from a sewer and fled the area in two separate vehicles, traveling northbound on Park avenue.

“There are no arrests at this time, and the investigation remains ongoing” the police said on Wednesday.

In August, the NYPD said it was investigating video footage showing several people climbing out of a manhole. It was reported at the time that investigators were considering the possibility that the individuals were “scouring the system for valuables that get into the sewage”.

In May, several people were also spotted entering and exiting manholes in Brooklyn.