"First we had to suppress the fuel tank, so it will not cause more danger, especially if it explodes."
The plane was on a test flight to Palawan province, according to radio reports.
The flight manifest showed seven people on board, including the pilot, but crash investigators were unable to confirm the number of people aboard.
Four bodies have so far been recovered.
Lita Velasco, whose house caught fire in the crash, said: "I ran to our burning house because my family was there so I gathered my relatives and ran."
The plane is owned by Victoria Air, which could not be immediately reached for comment.
The Civil Aviation Authority is investigating the cause of the crash.