Other boats in the area heard the radio calls from the duck boat run over by a barge last week, NTSB said in a statement released Monday.

In interviews with NTSB on Friday, the duck boat master said he tried to tell the tow boat guiding the barge to change course, but there was no response.

The fact that others in the area heard his call, which he said he made when the barge was 400 yards away, indicates that the fault more likely lies with the tow boat’s equipment or crew.

The duck boat had shut off its engine and set anchor because it was having engine problems.

When the barge hit the duck boat, the duck boat quickly sank. Two of the passengers were fatally injured. The other thirty-five people on board survived.

The two who died were Hungarian students, 16-year-old Dora Schwendtner and 20-year-old Szabolcs Prem. They were in the U.S. for an faith-based exchange program.