PHOENIX (REUTERS) - A lightning bolt struck a group of sightseers at an overlook near the Grand Canyon in Arizona, killing a couple who were visiting from another country and injuring a boy, authorities said on Wednesday.

The lightning struck at the LeFevre Overlook, about 48km north of the Grand Canyon National Park in northern Arizona on Tuesday, Coconino County Sheriff's Office spokesman Gerry Blair said.

"We believe there were a number of people at the rest stop, kind of milling around and looking... and a bolt of lightning came down and affected three people," Mr Blair told Reuters by telephone.

The unidentified man and woman, who were married, were pronounced dead at the scene. Their names and country of origin are being withheld pending notification of relatives, Mr Blair said.

The boy, who was travelling with another group of adults, was transported to an area hospital for treatment for non-life threatening injuries, he said.