In the wake of reports that Las Vegas mass killer Stephen Paddock also had booked a room in Chicago during this summer’s Lollapalooza music festival, Chicago Police on Thursday announced they would have a lot more officers on duty during Sunday’s Chicago Marathon.

That race, with about 40,000 participants and many more spectators, is falling in the middle of a busy weekend that won’t really end until Monday, when the Chicago Cubs have a playoff game at Wrigley Field the same night the Chicago Bears take on the Minnesota Vikings at Soldier Field.

Not to mention the throngs likely to pack the bars around Wrigley Friday and Saturday to watch the first two games between the Cubs and the Nationals, being played in Washington.

“Well over 1,000 officers have been added to the existing deployment,” police spokesman Anthony Guglielmi said of uniformed officers who’ll patrol Sunday’s race.

The Chicago Sun-Times has confirmed Paddock booked rooms at a Michigan Avenue hotel overlooking Grant Park during Lollapalooza, but he never showed up. Paddock was perched in a 32nd-floor hotel room Sunday night when he opened fire on an outdoor music festival in Las Vegas, killing 59 people.

“There’s not going to be any changes for the spectators,” Chicago Police Chief Anthony Riccio, who heads up the Bureau of Organized Crime, added at a news conference.

“That said, we learn from every event, every tragedy … we learned from Vegas as well. So one of the things that we’re doing is we’re putting [in place] a significantly larger number of undercover officers,” Riccio said.

“They’re going to be intermingled with the crowd, they’re going to be around the runners, they’re going to be in the finish line, they’re going to be in the start line,” he said. “So we’re going to have a significant amount of undercover officers that are going to be blending in there to keep an eye on things.”

The increased police presence will also be in place for the Bears game Monday and at large scale events for the “the foreseeable future,” Riccio added.

Although the potential link to Chicago raises questions, former Secret Service Agent Arnette Heintze said he does not believe “extraordinary steps” need to be taken — either to secure next year’s music festival or Sunday’s Chicago Marathon and Monday’s National League Division Series playoff game at Wrigley Field.

“Does this tragedy in Las Vegas highlight another area? Yeah, it does. Will they take steps to put in place counter-measures? They might,” said Heintze, founder and CEO of Hillard-Heintze, a Chicago-based security consulting firm. “The whole world now knows that a situation like this presents a concern. But the building is not the threat. It’s the people. What do we know about people exhibiting behavior” that poses a potential threat.

Alicia Tate-Nadeau, executive director of the city’s Office of Emergency Management and Communications, said law enforcement officers have been coordinating with security personnel from high-rise buildings along the marathon route.

“We don’t want to get into the tactics of how we’re going to secure [the marathon], but I will tell you that we do have a very robust plan in place,” Tate-Nadeau said.

Mayor Rahm Emanuel, who was asked if he was confident that all necessary marathon security measures were in place, responded: “Yea … 100 percent.”

He stressed the public’s role in reporting anything suspicious and echoed the law enforcement motto: “If you see something, say something.”