The FBI has raided City Hall in Union City.

Union City Mayor Brian Stack, also a state Senator, says the city is cooperating fully with an investigation by the FBI. (NJ.gov)

An FBI spokesman says agents are at the city's Community Development Agency as part of an ongoing investigation but would not provide more details.

The raid was first reported by The Star-Ledger. A spokesman for Democratic Mayor Brian Stack, who is also a state senator, tells the newspaper the city is cooperating fully with the investigation.

The Jersey Journal reports agents have seized computers, files and other records.

The northern New Jersey city has a population of about 67,000.