CHICAGO (CBS) — With the Bank of America Chicago Marathon less than 48 hours away, runners’ and organizers’ minds were focused on security Friday morning, in the wake of the shooting massacre in Las Vegas.

Chicago police have said they’re amping up the number of undercover officers who will be deployed along the marathon route, and Mayor Rahm Emanuel has said the city is “prepared for any eventuality” on Sunday.

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“We trained for any possible circumstances in this type of event so everybody can enjoy a great marathon,” Emanuel said earlier this week.

The mayor said the city’s Office of Emergency Management and Communications is double- and triple-checking security plans.

Race director Carey Pinkowski said he’s confident officials are prepared to respond to any potential problems.

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“There’s a great relationship between the event producers and the Chicago police and the federal agencies,” he said. “So we share best practices. We interact with the Chicago Bears, we interact with the Lollapalooza producers, and that sharing of best practices, we get a little bit better.”

Approximately 45,000 people will run the 26.2-mile race through 29 neighborhoods Sunday. About 20,000 runners are from Illinois; the rest represent all 50 states and 100 nations.

This year is the 40th Chicago Marathon, so organizers celebrated by honoring a group of men who have run all 39 previous races and are hoping to finish their 40th.

“The first one, it was just the challenge of it, plus it was the first one and I wanted to be able to say someday that I ran the first Chicago Marathon,” runner Larry Moon said. “I didn’t know I’d keep saying it every year.”

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The marathon’s Abbott Health & Fitness Expo on Friday drew more than 130,000 people looking to check out the latest in running shoes, apparel, nutrition and technology. Runners also showed up to pick up their race bibs.