A military transport plane that crashed after takeoff in the southern Philippines with nine people aboard sank 600 feet under water, too deep for divers to reach, a navy spokesman said Wednesday.

Navy Capt. Rosauro Gonzales said the wreckage of the C-130 was located 2.5 nautical miles southwest of Samal island, a short distance from Davao International Airport, from where the plane took off Monday evening.

Fishermen found body parts, a torn uniform, combat boots and other debris Tuesday.

Gonzales said search teams used fish-finding sonar to locate the sunken fuselage, but that it was too deep for divers to reach.

A Radio DZBB report said an underwater camera found no trace of the nine crew, which included two pilots.

Air force chief Lt. Gen. Pedrito Cadungog would not speculate on the cause of the crash, which came amid an ongoing military offensive against Muslim rebels in three nearby southern provinces. The insurgents are blamed for killing dozens of civilians and pillaging communities in the region last week.

Cadungog said the rebels were not believed to have weapons capable of bringing down a plane flying above a couple of thousand feet (meters), but that sabotage was “always a possibility.”

Davao police investigator Joel Parojinog said residents from a coastal village reported seeing a plane around 9 p.m. Monday “going down into the sea with flames on one of the wings,” followed by an underwater explosion.

The C-130 is one of only two operated by the Philippine air force. The other aircraft was grounded for inspection and military officials acknowledged the loss would have an impact on combat operations.