Mark Purslow, Cesar Chanal, Davy Morgan, Roger Stockton and his son Bradley are all dead.
This is the highest death toll in a single year since 1970, when six motorcyclists lost their lives.
A statement read: “ACU Events Ltd, the race organizers of the Isle of Man TT Races have confirmed that a full investigation process is followed for each of the serious incidents at the Isle of Man TT Races 2022.
“Investigations systematically analyze all aspects of these incidents using an established root cause methodology.
“A multi-professional team involving all partner organizations is reviewing the events that have occurred and recommendations on how the event will be run in the future will be made.”
TT Race Director Gary Thompson MBE, BEM said: “After each incident, we work tirelessly to understand the circumstances, establish key learning and implement changes as soon as possible.
“Any death in an event is a tragedy.
“As an organization, we promise to take all measures that can improve safety and to undertake them as soon as possible.”
Five dead at 2022 Isle of Man TT
A total of 265 riders have died at the Isle of Man TT since 1911.
1982 was the only year without a single death.
Welsh runner Mark Purslow, 29, was the first to die this year after a training accident. It was his second TT event.
Frenchman Cesar Chanal has been announced dead four days after a case of mistaken identity resulted in the mistaken name of Olivier Lavorel.
The passenger in the Lavorel sidecar remains in critical condition. Cavalier Chanal is dead. The TT apologized for his misidentification.
Davy Morgan, 52, from Northern Ireland, died as a TT veteran after starting 80 races.
Roger Stockton, 56, and his son Bradley, 21, from Crewe, were the fourth and fifth deaths.