The tournament is being played on the course that vaulted John Daly to fame when he won the 1991 PGA Championship.
Andy Bean and Fulton Allem were tied for fifth at 67 while the group at 68 included Tom Lehman, Fred Funk and Loren Roberts.
Roberts defeated Funk and Mark McNulty in a playoff last week to win his second Senior British Open title.
The course played much easier than a typical layout used for a United States Golf Association event. There was little wind, the greens were soft and the pin placements were relatively easy on the 7,316-yard layout, the longest in the history of the tournament.
"They want to just see what happens to the scores and then they go from there," Roberts said.
Norman birdied four straight holes on the front nine to get his tournament off to a good start.
"The conditions were perfect," said Norman, still seeking his first win as a senior golfer. "The greens were receptive enough to be aggressive with the shots. It was a good day for scoring."
Tom Watson, who at age 59 almost won the British Open two weeks ago, shot a 71.