Two of the victims of the Luxor balloon tragedy were customers of Peterborough-based tour operator Thomas Cook.
Eyewitnesses to the incident said they heard an explosion before a fireball plunged from the sky.
Thomas Cook Chief Executive Peter Fankhauser said: "What happened in Luxor this morning is a terrible tragedy and the thoughts of everyone in Thomas Cook are with our guests, their family and friends."
He said the company was working with local officials and a full investigation would be taking place.
While this investigation is under way, Thomas Cook UK has suspended sales of hot air balloon rides in Egypt.
Thomas Cook UK has opened a hotline for concerned relatives who have guests in resort - 0800 107 5638.