Nancy Scranton, Maria Hjorth and Giulia Sergas finished three shots off the pace at 3-under-par 69. Paula Creamer, Tina Barrett and Young Jo followed at 2-under-par 70.
Gulbis played the back nine first at Tres Marias Residential Golf Club and hit her second shot to 10 feet for a birdie at the par-4 11th. She then hit a wedge to 8 feet at the par-4 12th and drained the putt for another birdie.
At the par-3 13th, Gulbis landed her tee shot inside 5 feet and converted the short birdie try to make it three straight.
'Once I got through those holes it made the front nine a little easier,' said Gulbis.
Gulbis hit her approach to 8 feet for a birdie at the par-4 first and dropped her tee shot inside 5 feet for a birdie at the par-3 sixth.
'I am very fortunate that I have good distance off the tee,' said Gulbis. 'That definitely helps on a golf course like this. I had a lot of wedges today and you can fire at pins when you have short wedges in your hands.'
The 22-year-old then hit an 8-iron to 4 feet for a birdie at the par-4 seventh to lead after the first round of an LPGA Tour event for the first time in her career.
'It was good,' said Gulbis. 'I hit a lot of fairways and a lot of greens and had a lot of opportunities to make birdies. Hitting fairways is very important on this golf course and that made the course a little bit easier.'
Burks also started on the 10th tee and found trouble early with a bogey at the par-4 11th. She recovered at the par-4 17th, however, and chipped in for an eagle. Burks then ran home a 10-foot putt for a birdie at the par-5 18th to reach 2 under around the turn.
'That pretty much made the round,' said Burks. 'It was kind of one of those days where I got all the right breaks.'
Burks continued the hot streak with a birdie at the par-4 first and moved to 4 under with a birdie at the third. She then parred her way in for a round of 68.
Koch mixed five birdies with a bogey for her share of second.
Last week's winner Wendy Ward carded a 1-under-par 71 to join Dorothy Delasin, Charlotta Sorenstam, Angela Stanford, Marisa Baena, Young Kim, Chris Johnson and Dawn Coe-Jones in a tie for 10th.
Local favorite Lorena Ochoa had a rocky first round of 73 that featured five birdies, four bogeys and a double-bogey.
'I think that the first round is the hardest one and I am done with that,' said Ochoa.