According to the Boston Marathon database, 521 runners from Colorado registered for this year's race, including 102 from Denver.

Denver's Becky Stouder crossed the finish line with her training partner, Katherine Sullivan, and had moved to the baggage claim area some 200 yards away when the first explosion rang out, she said. Stouder said she and Sullivan were OK, but shaken.

Organizers in Colorado Running event may be taking a deeper look at security.

The Bolder Boulder is only 41 days away. Another event in Denver is set for the end of the month.

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