Video captures group entering manhole on Long Island

A group of people were spotted going into a manhole early Thursday morning on Long Island, according to Nassau County police.

Officers said they got multiple 911 calls at 1:15 a.m. about a manhole cover being removed near the intersection of Wantagh Avenue and Jerusalem Avenue in Wantagh. 

The police department responded but found no people or damage. 

"I find it weird people are going into the sewers," one Wantagh resident said. 

"That worries me that they are going down. Are they planting stuff?" a Wantagh resident said. 

Shoppers in a mall adjacent to the incident hope Nassau Police make arrests, and provide a motive. Some told CBS News New York it's unnerving, and they're not clear on what the goal of it is.  

It raises the question of whether the potentially dangerous trend is moving east to Long Island. 

There have been numerous similar incidents in New York City recently. 

Just last week, on Aug. 18, three people were caught on video emerging from a manhole across from Madison Square Garden and Penn Station.

Back in May, there were similar incidents in Flatbush, Williamsburg and Queens. People were seen wearing waders and using headlamps and car lights to guide them.

The city's Department of Environmental Protection previously said entering the sewer system is illegal and dangerous. Even if the infrastructure is safe, people should not climb down there.

"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," a statement read.

Police sources in the city said the people who are going into manholes may be treasure hunters or urban explorers.