(CNN) -- As thousands gathered to mark the one-year anniversary of the Boston Marathon bombings, one sight evoked memories of the attack that spurred widespread carnage: Suspicious bags near the finish line.
Police spotted the bags on Boylston Street -- not far from where two pressure-cooker bombs exploded exactly one year ago Tuesday, killing three people and wounded at least 264 others.
Eventually, both bags spotted Tuesday were deemed safe -- but the man carrying one of the bags been charged with possessing a hoax device.
But how are police preparing for this year's marathon, which takes place Monday? Given that the 26.2-mile course runs through eight cities and towns, how can police possibly prevent every suspicious item from slipping through?
The anniversary scare
The first clue that something was amiss Tuesday came when a police officer spotted a man walking barefoot in the rain down Boylston Street with a backpack. Police said he became very vocal and started yelling.
When asked what was in the backpack, the man told the officer it was a rice cooker, police said.
"We looked into the backpack, saw that it was what appeared to be a rice cooker, had the individual take the knapsack off, drop it on the street, and he was taken into custody," Boston Police Superintendent Randy Halstead said.
The man, in his early 20s, has not been publicly identified. He was arrested and charged with disorderly conduct, disturbing the peace and possession of a hoax device, Halstead said.
A bomb squad inspected the bag and deemed it safe.
"In the process of rendering that safe, we noticed a second backpack off to the side. Nobody claimed ownership of it. At that time, that bag was rendered safe."
Officials say they have gone to great lengths to make sure nothing like last year's attacks will happen again.
In Tuesday's incident, the superintendent said, the "training kicked in."
"I have utmost praise for my officer," Halstead said. That's what he's trained to do, that's what he did, and that's why I'm proud of the guys of this department."
For starters, there will be no backpacks or rucksacks on the course itself, said Kurt Schwartz, director of the Massachusetts Emergency Management Agency, told CNN last month.
"We didn't receive pushback about the no-rucksack rule," Schwartz said.
He also urged spectators to not carry large coolers or wear costumes or masks.
In preparation for this year's race, Schwartz said officials have traveled to other states and countries to examine their safety precautions at events.
The Boston Athletic Association, which organizers the marathon, said while backpacks and handbags are prohibited for participants, spectators are also encouraged to leave such items at home.
Containers with more than 1 liter of liquid, costumes covering the face, and bulky clothes such as vests with pockets won't be allowed.
And large flags or signs bigger than 11 inches x 17 inches are also banned from marathon venues. Marathon venues include the start and finish areas, the course, athletes' village and areas where official events are held.
Unregistered runners and cyclists intending jump into the race along various points are not welcome this year, either.
"We are aware that many people want to participate in some way in this year's Boston Marathon as a display of support," the BAA said in a statement. "But we ask that those who are not official participants to refrain from entering the course for the safety of the runners and themselves."
A massive enterprise
It will be an massive enterprise.
Runners this year will number 36,000 -- up from 27,000 last year. More spectators than ever before will also line the course, according to the athletic association.
Keeping that in mind, police will double the number of officers on patrol from last year; 3,500 of them will be among the crowd. They will be aided by 100 additional security cameras, and bomb-sniffing dogs.
"In this world, you never eliminate risk; you never bring it down to zero," State Police Col. Timothy Alben told reporters last month. "But we are working very hard at reducing that risk level and managing it to the best of our collective abilities."
Authorities have not disclosed how much the extra security will cost. All they will offer is that it will be "much greater" than last year's.
According to Greater Boston Convention & Visitors Bureau, the marathon and related events will bring in an estimated $175.8 million -- the highest-ever Boston Marathon spending impact.
CNN's Faith Karimi contributed to this report.
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