Following the deadly bombings at last year's Boston Marathon, new security rules are prohibiting bags, strollers, and unregistered runners from attending the race, CNN reported.

Last year, bombs placed in backpacks at the finish line killed three people and injured hundreds of others. As a result, backpacks, handbags, suitcases, and similar bags are no longer allowed.

Additionally, containers filled with more than 1 liter of liquid, costumes covering the face, and heavy clothing like pocketed vests are prohibited. 

The Boston Athletic Association issued a statement on Wednesday, detailing all of the updated regulations for the race scheduled for April 21. 

"We are aware that many people want to participate in some way in this year's Boston Marathon as a display of support," the statement said. "But we ask that those who are not official participants to refrain from entering the course for the safety of the runners and themselves." 

Though marathon runners cannot take any personal items near the finish line, they will be able to carry clear bags provided by the organization told medication, cell phones, and fluids. 

Any sign bigger than 11 x 17 inches will also be banned at all marathon venues. 

Earlier this month, the association announced plans for Mayor Martin J. Walsh to co-host a memorial ceremony marking the one-year anniversary of the marathon attacks. 

"On April 15, we recall the courage, compassion, and commitment of our great city and its people," said Boston Mayor Martin J. Walsh. "Through this event, Boston again stands as one: paying tribute to all those affected by last year's events and once again showing the world that Boston's  spirit of resiliency lives on."