MADRAS, Ore. (AP) — Oregon authorities have identified a married couple from Idaho as the victims of a small plane crash Sunday that killed both people on board.

A husband and wife from Caldwell, Idaho, were the two fatalities, the Jefferson County Sheriff’s Office said on Facebook. The office hasn’t released the victims’ names due to difficulties notifying their families.

The single-engine Piper PA-32 crashed Sunday night around 7:40 p.m. in a remote area of central Oregon outside the city of Madras, authorities said. The plane had taken off from Aurora, south of Portland.

The National Transportation Safety Board has opened an investigation into the crash. One of its investigators visited the site Monday to document the wreckage before it’s sent to a secure facility for further evaluation, the NTSB said.

The Federal Aviation Administration will also oversee the investigation, the sheriff’s office said.

Local power company officials found the wreckage after looking into a power outage in the area, the NTSB said in an email.

The agency said it expects to release a preliminary report on the accident within 30 days. The final version, which will include details about the investigation and the probable cause of the crash, is expected in 1 to 2 years.