The limb sheered off a red oak next to the green and a television tower at Baltusrol Golf Club and fell approximately 60 feet.
Frank Choy, a freelance audio technician working for Turner Sports, broke his left leg and was taken to a hospital. Bob Welsch, who was operating the jib camera under the tree, sustained abrasions to his left forearm and was treated at the site and released. A 60-year-old spectator, who asked not to be identified, was treated at the golf club's medical office for minor bruises on his left arm and released.
The limb fell moments after Tiger Woods played his approach shot on the par-3 hole.
The crowd was reacting to Woods' shot, which spun back toward the pin, and a roar went up as the branch began tearing away from the tree.
Play resumed after a delay of less than 10 minutes.
The tree was inspected and trimmed before the start of the tournament and construction of the greenside TV tower, tournament director Andy Bush said.
The PGA said the tree would be removed before Saturday's third round as a precaution.