(CBS) What happened in Las Vegas last weekend will be on many peoples’ minds at the Chicago Marathon this weekend.

Organizers say they constantly review their security measures, especially since the Boston Marathon bombing in 2013. The Las Vegas attack brings new challenges.

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Authorities say they’re confident that the plan they have in place is the right one, CBS 2’s Sandra Torres reports.

Chicagoan Henry Kozlowski is about to run his 40th Chicago Marathon. It has become an annual tradition for the 67-year-old and his friends.

He notes the changes he’s observed, including the security measures in place.

“There really was no security” in the earlier years, he says. “It was an open thing, people just kind of came around. It was very loose.”

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That’s no longer the case. Anthony Riccio, head of the Chicago Police Department’s Bureau of Organized Crime, says there will be a “significantly large number” of undercover police officers intermingled with spectators and around the runners.

Officials say they’re working with 38 different agencies — local and federal — to secure the route.

“As Monday happened, there’s been a double-, triple-checking,” Chicago Mayor Rahm Emanuel says.

Marathon participant Kozlowski  says he’s not concerned.

“Yhey are doing all necessary things,” he says.

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Authorities say they need the public’s help in remaining vigilant.