The Oklahoma Highway Patrol says all five people on board were killed when a small passenger airplane crashed in northern Oklahoma on Saturday, ABC News reported.

The cause of the crash was not immediately known, said Federal Aviation Administration spokesman Lynn Lunsford.

"A single-engine Extra EA-400 crashed under unknown circumstances ... shortly after taking off from Ponca City Regional Airport," Lunsford said in an email. "The aircraft was destroyed by a post-crash fire," at the site about 90 miles (145 kilometers) north of Oklahoma City.

The Extra EA-400 is described as a six-seat corporate aircraft with space for a one-person crew and five passengers.

The names of the victims were not released and OHP Lt. Kera Philippi said the fire obliterated much of the aircraft's tail number.

An OHP report said the plane was northbound from the airport about 10:45 a.m. Saturday when it "lost altitude and stuck the ground."

The bodies were sent to the Oklahoma medical examiner's office for identification. All were dead at the scene "due to massive injuries," according to the OHP report.

Philippi and National Transportation Safety Board spokesman Peter Knudson said the five had flown to Ponca City for a monthly breakfast hosted by the airport.

Airport manager Don Nuzum said the Ponca City Aviation Booster Club hosts a fly-in, drive-in breakfast the first Saturday of each month, but said he could not comment about the crash.

Lunsford said the FAA and NTSB will investigate the crash, with the NTSB leading the investigation.

Local media reported that the plane was registered in Kansas.

Knudson said an NTSB investigator was headed to the site Saturday, but it was not known when he would arrive.

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