The accident took place yesterday morning over Porthcawl, near Bridgend in South Wales, when Air Cadets Katie-Jo Davies and Nikkita Walters were taking part in air experience flights with the Air Experience unit based at MOD St Athan.
Air Experience flights take place throughout the year and form part of the National Curriculum, wherein students perform activities outside of their routine school work.
RAF spokesman Group Captain Andy Naismith said:
"Yesterday's tragic accident took the lives of four members of the RAF family. As I said yesterday, our thoughts are with the family, friends and colleagues of those who died.
"The aircraft involved in yesterday's incident were two Grob Tutor T1 training aircraft. These aircraft are supplied and operated by VT AE and have been in use as an elementary flying training aircraft by the RAF since 1999.
"The RAF is working closely with the Air Accident Investigation Branch and South Wales Police as part of a tripartite investigation. An MOD Service Investigation is already underway and all the data gleaned will be shared to enable us to determine the facts which led to yesterday's tragic accident.
"For this reason, you will appreciate that we cannot speculate about the causal factors which led to this accident. We must gather the facts to reach the proper conclusion.
"Members of the Emergency Services, the Environment Agency, Local Authority and the communities involved have provided unstinting support throughout last night's bitterly cold weather and, for their selfless contributions, I thank them for this and for the immense compassion everyone concerned has shown.
"The loss of four members of the RAF family is one that is felt acutely."
Defence Secretary John Hutton said:
"I was immensely saddened to hear about this tragic accident. At this extremely difficult time, the thoughts and sympathies of all those at the MOD and across the Services are with the four families who have lost loved ones.
"It is clear that the RAF pilots, Flying Officer Hylton Price and Flight Lieutenant Andrew Marsh, had a great love of the RAF and dedicated their time to sharing it with young cadets like Katie-Jo Davies and Nikkita Walters.
"Investigations are underway to establish the cause of this tragedy."