By Robin Culverwell

PHILADELPHIA (CBS) — Thirty thousand spots for May’s “Broad Street Run” were claimed in just five hours today, even as demand slowed the registration web site to a crawl.

Three thousand people with ties to the race sponsors were allowed to register early.  The open registration field is limited to 30,000, and organizers say it took four days to reach that capacity last year.

This year it was less than half a day, and race director Jim Marino says the demand to register overwhelmed their web site.

“The system just couldn’t take the weight of everybody trying to do it at the same time,” he told KYW Newsradio afterward.

Organizers plan to hold a lottery for another 2,500 spots, to be drawn the last weekend of this month.

Marino says it’s the course, the volunteers, and the runners who make the race great.

“We’re looking at 33,000 as a minimum,” says Marino, “and we’ll keep adjusting to make sure it’s safe for everybody out on the course.”

The ten-mile Broad Street Run steps off Sunday, May 6th, at 8:30am.