CHICAGO (WLS) -- As runners prepare for the Chicago Marathon this Sunday, security is on the minds of organizers and law enforcement agencies in the wake of the mass shooting in Las Vegas.
"We're confident we have a good plan in place, and we're willing to make any adjustments that will be necessary up until the start of the race Sunday morning at 7:20," said First Deputy of the Office of Emergency Management and Communications Richard Guidice.
Sunday's race will happen a week after the mass shooting in Las Vegas. On Thursday, reports surfaced that the shooting suspect booked two rooms at The Blackstone hotel during Lollapalooza last August. That hotel overlooks Grant Park.
Security is a major priority for organizers. Fencing is going up, and the number of undercover officers has increased.
"When something like that happens, security doubles up their efforts - so it's a good thing to be here at this time...when everyone is just wanting to make everybody safe," said marathon runner Maricel Laxa Pangilinan.
Before the Las Vegas attack, Homeland Security officials, the FBI and Chicago authorities put together a security plan for Chicago's marathon. ABC7 obtained a copy of the report, which detailed concerns about vehicles ramming crowds and attacks on public transportation.
"There is a great team here that understands events, and there is a great relationship with between the event producers and Chicago police and federal agencies so we share best practices," said Chicago Marathon race director Carey Pinkowski.
Organizers said runners and spectators should always tell authorities if they see something suspicious.
"There is no perfect security. Security comes in layers. It comes in improving the security of the people in the city of Chicago. And that is in fact what you're observing in the last few weeks," said Professor Robert Pape, director of projects on security and threats at the University of Chicago.
Larry Moon, 76, is celebrating a huge accomplishment. He has participated in every single Chicago Marathon. He has also run the Boston Marathon, and over years has noticed the security procedures change.
"You see all of the security out there before the race. Most of the runners are coming in from Michigan Avenue, you see Homeland Security, you see K9, everybody is out there," Moon said.
Moon said he always feels safe here and knows Chicago will be ready to handle another race weekend.
"Once I start running I don't even think about it," he said.
Forty thousand runners are expected to run in the marathon, and over one million people plan to cheer them on.
Security for Chicago Marathon increased in wake of Las Vegas shooting