BOSTON (CBS) – Tens of thousands of people are expected to attend this year’s Boston Marathon. On Thursday, law enforcement officers shared some of their plan to keep everyone safe.

“A lot of training went into this event, but I want to stress: there is no threat to this race. We’ll be as low key as we possibly can out there, but we’ll be ready if something should happen,” Boston Police Commissioner William Evans told reporters during a press conference at Boston City Hall.

The marathon security plan has evolved after terrorist attacks seen worldwide over the last year, Evans said. Security measures will include teams on rooftops and dump truck barriers.

“We don’t want to get complacent after what happened five years ago,” Evans said.

He joined Boston Mayor Marty Walsh, Boston Athletic Association CEO Tom Grilk, and other city officials for the press conference that detailed extensive security measures – including road closures, security checkpoints and bomb-sniffing dogs – to keep citizens safe on Marathon Monday.

“We’re asking for everyone’s help to make sure this is a great, safe, fun family event,” Walsh said.

Evans and Walsh called the safety plan in place “comprehensive.”

Mayor Marty Walsh: If you don’t have to bring a bag, don’t. If you do, make it a clear bag. #BostonMarathon #wbz pic.twitter.com/bf204wrey5 — Christina Hager (@HagerWBZ) April 12, 2018

Officials have planned for thousands of police to line the route of the race.

Several uniformed officers will line the route while others will be undercover.

Observations teams will be stationed on roofs with SWAT and hazmat teams along the course.

“Don’t fly drones,” Walsh said, adding that the FAA has declared the marathon route a “no-fly zone.”

Walsh asked for the public’s cooperation to make the day a safe one.

“Don’t engage in crazy behavior, don’t be on roof tops. We obviously don’t want any public drinking,” Walsh said.

Thirty-five security checkpoints will be placed along the route to check bags.

Evans and Walsh urged participants not to bring large bags to avoid long lines at security checkpoints.

“Do not bring bags and large containers… this will slow down the process,” Walsh said.

Law enforcement may close down some areas and reroute pedestrians in the case of overcrowded streets.

“We will be monitoring the course as the day goes on,” the mayor said.