WBRZ - Baton Rouge

An idled tour boat and nearby vessels repeatedly called the tugboat guiding the barge that hit and sank it, killing two Hungarian students, that's according to a preliminary federal report.

The National Transportation Safety Board said the Ride the Ducks boat's radio calls went unanswered moments before the collision in the Delaware River in July.

35 passengers and two crew members were about the amphibious boat when it sank.

Drug and alcohol tests on crew members of both vessels came back negative.