A balcony packed with students collapsed during a party at a house near Trinity College in Connecticut, injuring about 30 people, police in the US said.
Deputy Chief Brian Foley, of Hartford police, described those hurt as "walking wounded" and said most were students.
He said authorities received numerous calls on Saturday night of multiple people hurt at an off-campus house after the third-floor balcony collapsed - crashing into balconies on the second and first floor.
Mr Foley said each balcony was crowded with partygoers. He described the collapse as like white tubing from a "three storey beer bong".
The injured were sent to five area hospitals, Mr Foley said, with the most serious reported injuries being a broken arm and a head injury.
"That's some pretty weighty decks that fell down," Mr Foley said. "We're very lucky there weren't worse injuries."
He said the third-floor balcony showed signs of deterioration.
"At this point, the third floor, you look and see the wood was very rotted and very old and structurally not very sound," he said. "Then you get 50 or 60 kids partying out there and it's obviously a dangerous situation."
Off-campus party caused deck collapse. HPD and HFD responding. pic.twitter.com/D1jhxoRD6Y— Brian Foley (@LtFoley) September 11, 2016
The building, located a short distance from the Trinity campus, was owned, but not managed, by the college.
Hartford Mayor Luke Bronin said it was lucky there were no fatalities.
"There are dozens of injuries, but we are very lucky that there were no fatalities and no known critical injuries from what could have been a truly tragic incident," he said.
The mayor said police and firefighters were on the scene within minutes of the accident and that first responders worked quickly to get the injured transported to hospitals.
Trinity College is a liberal arts school in Hartford with about 2,200 students. It's the second-oldest college in Connecticut after Yale.