Rangers said they received a report of the lightning strike shortly before 3 p.m. at the Bright Angel Trailhead.
A 30-year-old man and a 28-year-old woman were found unresponsive. The man regained consciousness without intervention, but the woman did not regain a pulse until CPR and advanced life-saving efforts were performed.
The woman was later recovering at a regional burn center, but the man’s condition was not immediately known.
Grand Canyon rangers say at least two other people took themselves to the Grand Canyon Clinic with lightning splash injuries.
A lightning splash occurs when lightning strikes a taller object near someone and part of the current jumps from the object to the person, according to the National Weather Service.
In Grand Canyon National Park alone, lightning strikes an average of 25,000 times each year. The NWS says lightning kills 49 people each year, on average, and hundreds more are injured. Survivors can suffer from lifelong neurological damage, the agency explained.
Earlier this month, monsoonal weather claimed the life of a Michigan woman who became caught in flash flooding activity in the Grand Canyon.
Two people were also recently struck by lightning in a Utah state park near Canyonlands National Park, and just over a year ago, a Utah man was struck by lightning while on a walk in Eagle Mountain.