The Ventura County District Attorney’s Office and the FBI raided the Oxnard City Hall on Friday, but few details have yet to emerge as to why the investigation took place.

Investigators served search warrants and interviewed numerous city officials in the raid while hard drives and stacks of city documents were carried by investigators out of city hall.

While neither agency gave details regarding the investigation, The Ventura County Star reported that investigators were seeking information on a Groundwater Recovery Enhancement and Treatment Program, a $250 million endeavor.

The Star reported last year on cost overruns, contract irregularities and an elaborate grand opening party regarding the project.

“I’m completely caught off-guard by this,” Mayor Tom Holden told the Star. “You have to keep in mind that I haven’t been questioned by the DA. I’m at a loss for words of what is happening.”

The newspaper reported that investigators searched the Human Resources Department, the City Attorney’s offices, the City Administrator’s offices and the Public Works Department.

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City Clerk Daniel Martinez said investigators requested financial forms from his office. Among them was the Form 700, which are statements of financial interest that track not just business interests of top officials and City Council members, but also property owned by those officials and any gifts they received.

Martinez said they requested other records, including council minutes and resolutions and several items that deal with public works and contracting.