Military authorities have launched a full-scale investigation into the crash of a maritime patrol aircraft in the southeastern city of Pohang that killed all four Navy officers on board. 

According to the Navy on Friday, the authorities have put out the fire that started Thursday at the crash site and retrieved the bodies. 

The authorities installed lighting at the crash site Thursday night to retrieve evidence that could shed light on what caused the accident, such as the black box. 

They plan to determine the cause of the accident by analyzing communication records obtained through forensic investigation.

Military authorities are also seeking to identify the bodies through DNA analysis, as they were severely damaged in the crash and the fire.

The P-3C maritime patrol plane crashed on a mountain in Pohang around 1:50 p.m. Thursday, six minutes after lifting off from the Pohang naval base for a training mission.