NEW YORK (CBSNewYork) – Two trucks and a bulldozer were set ablaze Saturday at a New York City Department of Environmental Protection water supply facility in Manhattan, police say.

Authorities called the fire suspicious and said they were searching for two persons of interest.

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Heavy smoke billowed into the air under the Manhattan Bridge.

“Wow, that’s insane, that’s very insane. I can’t believe that actually happened,” Two Bridges resident Jack Morris told CBS2’s Reena Roy.

Investigators said two people set the equipment on fire around 3:15 p.m. at the lot on Madison and Pike streets.

“I think it’s really crazy that people would actually try and do that, it’s really just sad,” said resident Denise Perry. “It makes no sense to do anything like that.”

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Two employees saw the smoke and called 911. Police said it’s lucky no one was hurt.

“It’s just wild. This is a congested area, you know what I mean. It could cause health issues, safety hazards, the train’s right there, too,” resident Tom Travers said. “I guess I’m just wondering why.”

A sign clearly says it’s a private city property. Investigators do not believe the fire was started by employees.

The NYPD was standing guard there Saturday night, keeping a close eye on the lot.

Police are reviewing surveillance video in hopes of tracking down the people responsible.

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FDNY fire marshals are also working to determine exactly how the fire started.