Thousands of people ran, walked and partied on the city streets of San Francisco as they celebrated the 100th annual Bay to Breakers race May 15.

The 12K race hosted two types of crowds: the serious runners and those there for the famed costume aspect of the event.

Headlining the more conventional portion of the footrace was Moroccan Ridouane Harroufi, who finished first in the men’s group, and Kenyan Lineth Chepkurui, who finished first among the women.

Joel McDonnell, 23, was among the serious runners at Bay to Breakers. He decided to participate because he enjoys running and said the event was exciting.

“It was pretty amazing the amount of people that were there,” he said.

McDonnell trained for more than a month prior to the race, carving out spare time from work and going to Academy of Art University. His training consisted of five-mile runs that over time were replaced with seven-mile ones.

“It wasn’t as hard as I thought it would be,” McDonnell said. “The hill of Hayes really separated the competition though.”

He finished the race in 59 minutes and 38 seconds and plans on participating again next year.

“I have to beat my record,” McDonnell said.

But for many, like 28-year-old Jennie Waskey, Bay to Breakers is part of San Francisco’s tradition of fun — not competitive sports. Waskey said she has consistently attended the race since the second grade.

“It started up as a family thing,” Waskey said. “Then it was about hanging out with friends.”

The more relaxed participants were focused solely on having a good time at the historic event.

Many locals who played home to the event warmly embraced the crowd by providing music while others offered drinks. A woman near Hayes Street yelled “Get your Jell-O shots!” as people passed by.

Although law enforcement and the Zazzle Bay to Breakers website said that alcohol would not be allowed, many attendees found ways to drink. As a result, many people were visibly intoxicated halfway through the race.

Elsie Williams, a San Francisco resident and 20-year Bay to Breakers participant, said that the race event has become more and more about partying.

“It’s gotten wilder over the years,” Williams said. “There’s more naked people. But it’s always fun.”

Every year Williams and her friend Claire Rovegno design and build tall hats to wear at Bay to Breakers. They said this year was special because it was the 100-year anniversary of the event.

For first-timer Bob Stinson, 24, attending the race gave him and his three friends from Arizona the chance to meet up and have some fun.

“They heard this might be the last one, so they decided to come out,” Stinson said. “I never knew it was that big of a deal.”

The streets were filled with numerous characters, including: bees, Waldos, salmon “swimming” the opposite way, Care Bears, gnomes and even more coordinated efforts like a group that showed up dressed as the cast of the animated movie “Up.”

Rosenne Stanford, 28, and 99 of her Harvard Business School classmates flew in from Cambridge, Mass., to be part of the San Francisco race. All 100 students attended Bay to Breakers dressed up as gnomes, wearing red underpants inscribed with their group name, “the underpants gnomes.”

“Harvard can be kind of boring, so we needed some fun,” Stanford said.

San Diego resident Chachee Ramos has been coming out to Bay to Breakers for seven years in a row now and said the race captures the city’s atmosphere.

“Bay to Breakers brings people together and symbolizes San Francisco in one day,” Ramos said.

Police officers were present along every intersection of the route and many participants were asked to dispose of their alcoholic beverages.

Long Fung Chung has worked at Bay to Breakers with the American Red Cross for the last eight years and said he has seen some change this year.

“People are better behaved this year,” Chung said. “People used to lay down on the streets.”

The American Red Cross placed eight first aid and emergency stations throughout the race course. Chung said the biggest ailments people needed help with were blisters, cuts from falls, headaches and dizziness.

SF State student Jessica Schimm attended Bay to Breakers for the first time this year and said her favorite part of the event was the unique outfits.

“The best part was seeing all of the different costumes,” Schimm said. “The ‘Black Swan’ costumes were one of my favorites.”

She said other SF State students should experience Bay to Breakers.

“I would definitely recommend it to SFSU students,” Schimm said. “It’s like a rite-of-passage living in San Francisco.”