FREMONT, Neb. (AP) — A small plane appeared to have struck a power line before it crashed into the Platte River in Nebraska and killed all three people aboard, according to the National Transportation Safety Board.

Few details are available about the Friday evening crash because it is early in the NTSB investigation. The agency’s preliminary report is expected in a few weeks, but the final report identifying the cause likely won’t be done for more than a year.

Fremont Airport officials told KETV that the plane was flying without its transponder being turned on, but Scott Vlasek, the director of the University of Nebraska-Omaha’s Aviation Institute, said that might not have been required because the plane was flying in uncontrolled airspace along the river.

Investigators will examine the maintenance records for the 71-year-old Cessna 180 for any sign of mechanical problems that could have contributed to the crash.

The Dodge County Sheriff’s office identified the three people killed in the crash as Daniel Williams, 43, of Moundridge, Kansas; Jeff Bittinger, 50; and Randy Amrein, 48. Both Bittinger and Amrein lived in Fremont, Nebraska.