As a thousand people descended on Old Campus — students with painted faces and residential college T-shirts, bewildered or amused parents visiting for the weekend — no one was certain whether it would actually happen.

Students chanted their college cheers and stretched their quads, waiting for the appointed hour, 4 p.m., to see if all those mysterious e-mails and fliers heralding the return of bladderball were just one big hoax.

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But right on time, a multi-colored six-foot ball bobbed through Phelps Gate. There was no mistaking: ban or no ban, Bladderball was back.

The game, which meandered from Old Campus to Cross Campus, soon blocked traffic on Elm Street, bloodied a few noses and brought out the police for about 40 minutes until the bladderball deflated. Afterward, some students continued fighting over the scraps.

“This is the most amazing event ever,” Freddy Ketchum ’13 said from atop the Women’s Table as throngs of students tugged at the remnants of the ball below. “I have never been a part of something so glorious in my life.”

Though some students expressed concerns about safety, many said they were enthusiastic about the return of the tradition, which was officially banned 27 years ago.

As the blue, green, red and yellow ball bounced on the sea of outstretched arms in the middle of Elm Street, confused motorists honked their horns or, like New Haven resident Corrie Poland, took pictures on their cell phones.

“It’s not every day you run into the middle of a riot,” said Poland, who was on her way to a shopping errand.

One family in search of a parking space found one — in the middle of Elm Street. Metro Taxi 147, which was also detained, left the meter running, much to chagrin of the passengers in the back seat.

A Yale parent, Laurie Lieberman, said she thought the event seemed dangerous. But other parents, like Cliff Levine and Katrin Czinger, both with students in Timothy Dwight, joined in the game, following the ball along with the mass of students involved.

“TD will ultimately win it,” Levine declared.

At 4:24 p.m., three police motorcycles and two officers blocked off Elm Street from York Street to College Street, pushing students and parents off the road.

“Get out of the street,” they shouted.

Minutes later, students tore the covering off the ball, punctured it and eventually ripped it into shreds. Even though the ball was deflated, students continued to tug at it on Cross Campus, hoping to bring back a scrap to their respective residential colleges.

Although it was unclear which college “won,” most claimed victory in e-mails shortly after the event. Davenport, for one, said it posted 2,700 points.

After the game, the Wikipedia entry for “bladderball” was edited more than 160 times. The name of the winning college changed constantly until one editor locked the page at 5:51 p.m. because of “excessive vandalism.”

Although many students interviewed said they were excited to have the tradition back, some left the game with physical injuries.

“It’s as scary as I expected it to be,” Andie Levien ’12 said. “I was in the middle of a crowd for a second, and I got hit in the face many times.”

Max Budovitch ’13, who had blood on his face, said he was “smacked” right after the game began. Josh Pan ’12 said he thought the game was fun until he saw an elderly man being shoved against a car.

“Usually everybody’s so under control,” Jack Li ’12 said after exiting a crowd of students fighting for a part of the ball. “But on this occasion, everyone just shows their wild side.”

Berkeley College Dean Kevin Hicks would not let the warring students into his college.

“There was a little bit of danger involved of 300 people trying to mash themselves though the gate,” Hicks said.

The largest piece of the ball, a big carcass of blue tarp, ended up in the Ezra Stiles’ master’s house, where parents had gathered for a Family Weekend reception. Sweaty students displayed it on the banister. Two blue pieces of the ball hung above the entry to the Pierson dining hall servery Saturday night.

Deputy Secretary Martha Highsmith, who is in charge of campus security, could not immediately be reached for comment.

E-mail Cross Campus with photos, videos and written accounts of your bladderball experience or post them in the comments here.