ORANGE -- FBI agents raided Orange City Hall on Wednesday morning and the building was shut down as the investigation into alleged fraud and money laundering continues to unfold.

A sign on the front door said the building would be closed temporarily "due to unforeseen circumstances." A federal agent was guarding the doorway and would not let reporters enter the building.

"This morning, a search warrant executed by the FBI in the City of Orange Township," city spokesman Keith Royster said in a statement to NJ Advance Media. "City Hall is closed Wednesday, but will be open tomorrow morning, January 12 at 8:30 a.m. The City is cooperating with authorities."

Royster said Mayor Dwayne Warren closed city hall "in order to give the authorities unfettered access to the building.

The FBI and IRS confirmed the agencies are conducting official business at city hall, but would not provide any further details. Agents from the federal Department of Housing and Urban Development's Office of Inspector General were also seen at city hall Wednesday.

An official was seen taking photographs of the municipal building's exterior.

At least four unmarked federal law enforcement vehicles were in the city hall employee parking lot. It was not immediately clear what documents the agents were seeking...