A weekend of mayhem at the annual Talkeetna Moose Dropping Festival has left one young man presumed dead, others injured and dozens of locals wondering what happened to their one-time family-friendly fundraiser.

"Basically, Talkeetna became unglued," said Alaska State Trooper spokeswoman Megan Peters.

The most serious incident was when 22-year-old Jacob Larson, of Nikiski, jumped into the Susitna River at about 3:30 p.m. Sunday and disappeared. Troopers and volunteers have been looking for him but now believe he is dead, Peters said.

Larson and two other men were jumping off railroad pilings -- where the Alaska Railroad crosses the Talkeetna River -- when Larson was swept away. The other men ran along the riverbank trying to keep Larson in sight, but he soon disappeared around a bend of the Susitna River, troopers said.

Peters said the mayhem was so bad that troopers busy with the search for Larson were called away from the river to help with the disturbances on the streets.

The Moose Dropping festival is an annual benefit for the Talkeetna Historical Society. This year's was the 37th celebration and residents say it drew record numbers who overwhelmed the tiny town, population 850.

Tourists escaped the heat inside the local bakery or pizza parlor early Sunday afternoon. Seniors in crisp white sneakers shared the dusty street with shirtless dudes wrapped in tattoos as a young father threw rocks in the river with his son. A crew of young men shouted and danced and drank beside their car.

Things got bad at night, troopers said.

The streets smelled of beer. Liquor bottles were strewn along the river's edge where illegal campsites were set up. And, allegedly, according to Peters, one group of outsiders went from campsite to campsite hassling other campers.

Another event, Talkeetna's annual Bluegrass Festival, used to draw a rough crowd looking to party until troopers planted a firm presence and started cracking down on underage drinking, DUIs, and fights. The Moose Dropping festival was traditionally more about family, vendors and the history of the old gold-mining town --- until this year, apparently.

Amanda Randles, a bartender at the Fairview Inn, said the town "was just hit by an unbelievable amount of people."

At one point, she went to a window on the second floor of the inn and looked out. "It reminded me of Times Square New York," she said. "It was chaos."

Lauri Stec, a 15-year-resident of Talkeetna and the manager of Nagley's General Store, said the weekend was not a good time. "There was a lot of drunken, high, stupid people doing stupid things."

Stec's bicycle, always parked unlocked outside the store, was stolen. The thief "was one of those 'groovy people,' who pretends to be all groovy, kind and good. Well, if he was so good, why did he steal my bike?"

Stec said she's heard the organizers of the festival are seriously reconsidering what to change next year to avoid the mayhem.

Calls to the historical society were not returned Monday.

Resident Julia Crocetto said she's writing a complaint letter. Too many people showed up with their four-wheelers and loose dogs, she said. People removed clothing in the heat. And there was just a lot of noise, she said.

"I was on Main Street and every time you turned around, there was an ambulance coming towards you," she said.

She said she doubted that the outsiders who descended upon the quirky, picturesque town, most likely from Anchorage and other parts of the Mat-Su Valley, were there to help raise money for the historical society.

Peters didn't have specifics on the number of arrests or people injured. She said troopers on Monday were still very busy with looking for Larson and drawing up the paperwork from the weekend.

By MEGAN HOLLAND and KYLE HOPKINS