Marcus Higley, Adrien Bernadet, Mikko Korhonen and John E. Morgan are one shot back at minus-2.
Steven Jeppesen, Jan-Are Larsen and Gareth Maybin share sixth place. Those three are the last players in red figures at 1-under-par 70 on the Val Course at Aa Saint Omer Golf Club
With many of the top players in the world playing the U.S. Open this week, the field this week was filled by players from the European Tour as well as the Challenge Tour.
Kakko started on the back nine and opened with a pair of pars. He dropped in his first birdie putt on the par-four 12th. Kakko reeled off 10 straight pars from there.
The 26 year old from Finland sank his second birdie at the fifth. Kakko birdied the par-5 ninth, his last, to gain the first-round lead.
'I was really pleased with my round, and not dropping any shots was the key,' Kakko stated. 'I putted well and didn't make many mistakes, which was pleasing in weather like this. I teed off at 9:30 a.m. (local time), so it wasn't as bad for me as the guys who went out early. But it was still pretty bad.'
Higley traded a bogey for a birdie from the 11th to open his round. After eight pars in a row, he dropped a shot at the third. From there, Higley birdied five, seven and nine to share second.
Bernadet also started on the back nine. He birdied the 11th, but gave that shot back at the 13th. The Frenchman came right back with birdies at 14 and 16. After seven straight pars, he faltered to a bogey six, but rebounded to birdied his last, the ninth.
Korhonen had a bogey-free front nine with birdies at one, five and nine. He tripped to a bogey at 11, but rebounded with a birdie on 15. Korhonen dropped another shot at the last to finish at minus-two.
Morgan had a fairly benign round. He parred the first eight holes of both nines, then birdied the ninth and 18th to share second.
The Englishman has lost his playing privileges, but it wasn't a case of losing his game. In 2004, he was diagnosed with epilepsy.
'The epilepsy obviously set me back a fair bit, and unfortunately I can't really control it. It's in my brain, and if it wants to come alive, then it will,' Morgan explained. 'In the last three weeks, I've had three fits, so I'm not sure it's really under control. It's been difficult. On one of the recent Challenge Tour events, I had a fit on the practice ground just before I was due to tee off. Luckily for me, they let me tee off five minutes late.
'But I guess it's one of those things. All I can do is keep plodding on. Hopefully one day I get my chance again, and hopefully I take it. I'd love to be back on the European Tour again, and I think I can get there.'