Many of those on board had only recently completed basic military training, AFP reports.
Defense Secretary Delfin Lorenzana said rescue and recovery efforts were ongoing. The aircraft had 92 people on board, including three pilots and five crew and the rest were army personnel, military officials said. The pilots survived but were seriously injured.
The Lockheed C-130 Hercules was one of two ex-U.S. Air Force aircraft handed over to the Philippines as part of military assistance this year. It crashed on landing shortly before noon Sunday in Bangkal village in the mountainous town of Patikul in Sulu province, military chief of staff Gen. Cirilito Sobejana said.
Sobejana said at least 40 people on board were brought to a hospital and troops were trying to save the rest.
Initial pictures released by the military showed the tail section of the cargo plane. The other parts of the plane were burned or scattered in pieces in a clearing surrounded by coconut trees. Soldiers and other rescuers with stretchers are seen dashing into and from the smoke-shrouded crash site.
The plane was transporting troops from southern Cagayan de Oro city for deployment in Sulu, Sobejana said. Government forces have been battling Abu Sayyaf militants in the predominantly Muslim province of Sulu for decades.
It was not immediately clear what caused the crash