Six spectators were injured when lightning struck a tree during the Tour Championship at East Lake in Atlanta on Saturday, a PGA Tour official said on American broadcaster NBC.
The network said the spectators were hit by falling debris as the result of a lightning strike about 28 minutes after play had been halted during the third round.
The PGA Tour has suspended the third round for the remainder of the day.
"We had simultaneous lightning strikes, one at the maintenance area and one right near the 16th tee and driving range," said tour rules official Mark Russell.
"From my understanding it hit a tree and knocked debris off that tree, and that's what injured six people who were in the gallery.
"The EMS (emergency medical services) people were right on the spot. They got the injured people off the property in 15 minutes. As we understand now there are no life-threatening injuries."
The injured were taken to hospital, said NBC, which screened footage showing the lightning bolt that apparently caused the injuries.
Professional golf tournaments became far more vigilant about stopping play when lightning is nearby in the early 1990s after two spectators were killed at separate major championships in the United States in 1991.
One man was killed at the 1991 U.S. Open at Hazeltine in Minnesota, another at the PGA Championship at Crooked Stick in Indiana.
But while players and caddies are loaded into vehicles and taken back to the clubhouse in such situations, fans are left to seek their own shelter.
Watch the PGA Tour on Sky Sports Golf