The three British people were killed after a tourist helicopter crashed in the Grand Canyon in the US state of Arizona.
The British Foreign Office said it was providing support to their families and those of three more Britons who were injured.
A Foreign Office spokesperson said: "We are providing support to the families of six British visitors involved in a helicopter accident at the Grand Canyon on Feb. 10, and we are in close contact with the US emergency services."
The aircraft came down at about 17:20 local time (00:20 GMT) on Saturday. It is not clear what caused the crash.
The helicopter was operated by tour company Papillon Airways, reports said.