Federal agents raided an engineers union headquarters in West Caldwell Tuesday and union staffers are still trying to figure out why.

According to Assemblyman Thomas Giblin (D-Essex), agents served a search warrant to the Operating Engineers Local 68. Giblin, the former union president, manages the union. Giblin says agents took out different records, including minutes of union meetings, payroll records and contracts with employees throughout the state. However, Giblin doesn?t know what the agents were looking for or what they are investigating.

The union represents stationary engineers or boiler operators. The U.S. attorney?s office has not revealed any details of the investigation. Giblin believes the government must have received a complaint about the union. He adds he and his staff are cooperating fully with the probe.