New York officials arrested two of three men who they said were seen emerging from a manhole, exiting the city’s underground sewer system on Wednesday.

The New York Police Department (NYPD) arrested 26-year-old Kevin Rodriguez and 25-year-old Samuel Reveron on charges of conspiracy and trespassing.

Three men were seen exiting a manhole near the hotel where Israeli Prime Minister Benjamin Netanyahu was reportedly expected to stay for the United Nations General Assembly.

In a statement to the BBC, the NYPD said it had seen a number of incidents involving people going into the sewer system to look for valuables and scrap metal after a storm.

“This incident fits that same criteria, but out of an abundance of caution given the U.N. General Assembly and the sensitivity of the location, the NYPD is conducting additional security sweeps with our federal partners,” the police department said in a statement.

Rodriguez and Reveron, both from Queens, were arrested on Thursday. They allegedly fled the scene after climbing out of the manhole when officers were called around 4:30 EST (9:30 BST) on Wednesday, police said.

During a hearing on Friday morning, the two men pleaded not guilty and were released from custody, according to court records.

The arrests follow a string of incidents in which people were seen emerging from pavement manholes in different parts of the city in recent months.

In August, surveillance footage showed a person coming out of a manhole in Queens early in the morning. The same month, the NYPD said it was investigating three people wearing overalls and headlamps seen climbing out of a manhole near Penn Station.

In May, a group of people were captured on surveillance footage shifting a manhole cover and climbing down into the sewer in South Brooklyn.

Going into the New York sewer system is both illegal and dangerous, officials have said, cautioning that there is a risk of toxic gases and flooding in a confined space.

“For these reasons, members of the public should never enter a pipe, drain, catch basin, manhole, or outfall,” the city’s Department of Environmental Protection previously told the BBC.

This year, a woman died after she opened her car door and accidentally fell into an open manhole in Midtown Manhattan.