(CNN)Authorities have discovered the crashed wreckage of a small Cessna airplane after it failed to return to Billings, Montana, Saturday evening as planned.

Investigators are working to determine how many passengers were aboard the 1978 model Cessna 182 when it went down, Yellowstone County Sheriff’s Office Capt. Kent O’Donnell told CNN. He added that it was a private, recreational flight.

The FAA and the NTSB are also investigating the crash, which occurred around 6 p.m. (8 p.m. ET) about 25 miles north of Billings, FAA spokesman Allen Kenitzer said. As of Sunday afternoon the circumstances surrounding the crash were unknown.

Officials kicked off a search by air and ground at sunrise Sunday morning when the aircraft failed to return to Billings, O’Donnell said.

The wreckage was found just after 9 a.m. (11 a.m. ET) in a “somewhat rugged area,” O’Donnell said, adding, “accessibility will be a factor” in the investigation. Cell phone service in the area is poor, he said.

A 1978 Cessna 182 can typically hold up to four passengers, according to CessnaOwner.org.

CNN has reached out to the Billings Logan International Airport, where the plane took off.