The city of Duluth has vastly strengthened security for its celebrated Grandma's Marathon events this weekend, in the wake of the Boston Marathon bombings, the Duluth News Tribune reports.

Visitors at the 37th annual event will notice more police, the newspaper reports. Federal, state and county officers, and the Coast Guard, are helping local officers. Walk-throughs are being done to sweep for anything unusual. There are more cameras on the course, the newspaper reports.

And fans cheering on their friends and family won't be allowed to have bags in the stands at the finish line, the News Tribune reports. Runners will need photo IDs to pick up race packets, and they'll be given clear plastic bags to use for any belongings they take on shuttles to starting areas.

“It’s changed our operation,” Duluth Police Lt. Eric Rish told the newspaper. “We’re taking any measure that’s plausible.”

Three people were killed and more than 240 injured in the bombings at the Boston Marathon on April 15.

Urban marathons, with fans and runners spread out along 26.2-mile courses, are tough events to secure, organizers say. But the Boston bombings have changed the way race organizers nationwide view security. Bomb-sniffing dogs will accompany about 20,000 runners in this weekend’s Rock ’n’ Roll Seattle Marathon, the Seattle Times reports.

Grandma's Marathon starts at 7:45 a.m. Saturday, and a half-marathon event starts at 6:45 a.m. A 5K is planned for Friday night. More than 17,000 runners are expected in Duluth this weekend.