The FBI has questioned Hawaii school bus contractors and requested documents, apparently as part of an investigation into whether the businesses colluded to push up the cost of services.

Several contractors said they had been contacted by the FBI about six months ago to discuss the bidding process for school bus contracts. They said they are cooperating with the FBI.

The FBI declined to confirm an investigation is ongoing.

Lindy Akita, chief executive officer of Akita Enterprises, said agents interviewed him and several other contractors and asked for documents, which Akita said he provided to the FBI.

Akita said after the initial interview, however, he was not contacted again and doesn’t know the status of the investigation.