Six passengers and a pilot were on board the Papillon tour helicopter when it came down in the Grand Canyon West area at about 5.20pm on Saturday.
The four survivors were being treated at the scene.
They were all in a critical condition, but could not be airlifted out of the canyon because of high winds.
Photos of the crash scene showed flames and dark smoke rising from the rocky terrain.
Federal Aviation Administration spokesman Allen Kenitzer said the Eurocopter EC130 aircraft sustained considerable damage.
The FAA and the National Transportation Safety Board will investigate the crash.
Papillon Airways says on its website that it is "the world's largest aerial sightseeing company" and that it provides "the only way to tour the Grand Canyon".
The company says it flies around 600,000 passengers a year over the Grand Canyon and on other tours.
It also says it "abides by flight safety rules and regulations that substantially exceed the regulations required by the Federal Aviation Administration."
A Papillon helicopter was previously involved in a fatal Grand Canyon crash in 2001.
The pilot and five tourists from New York were killed, while one woman survived.