Through 36 holes, both players were 12-under-par 132.
In Friday's second round, Kerr shot 8-under 64, while Hjorth, the first-round leader, shot 5-under 67.
"It was a lot of fun. Not necessarily a relief," Kerr said about her round. "I mean I have been playing well for a very long time."
Il Mi Chung shot 4-under 66, and was alone in third place at 11-under 133.
Nina Reis (68) and Seon-Hwa Lee (67) shared fourth at 10-under 134.
Seventy players made the 36-hole cut of 1-under 143.
Defending champion Pat Hurst missed it after a 2-day total of 2-over 146.