Folks who come to watch the Bolder Boulder this Memorial Day will be subjected to intensified security, police said this week.

In the wake of the Boston Marathon bombings last month, officials announced stepped-up measures for the May 27 run. Roughly 50,000 runners are expected to participate this year and thousands more will line the course and fill Folsom Field for the finish.

University of Colorado police say spectators shouldn’t bring backpacks or other bags to the 10-kilometer race. “If people must bring bags, please pack lightly and keep them in your possession at all times,” the CU police department said in a statement. “’Airport rules’ will apply, and any unattended bags along the course or at Folsom Field will be subject to confiscation.” Only soft-sided bags smaller than 12 inches by 12 inches by 12 inches will be allowed inside the stadium. The list of permitted and prohibited items can be found here.

“We realize that the recent events in Boston have created some extra concern for people, and we want to reassure everyone that the Boulder and CU police departments and race organizers are working together to make this event as safe and enjoyable as possible,” Boulder Police Chief Mark Beckner said in a statement. “We have comprehensive security plans in place. We will not be discussing details or specifics of those plans.”

This year is the Bolder Boulder’s 35th anniversary. For race-day updates—including start times and maps—check here.

—Image courtesy of Shutterstock