An apartment balcony crowded with birthday revelers collapsed early on Tuesday near the University of California at Berkeley, hurling five Irish college students and an American friend to their deaths and injuring seven others, authorities said.
The victims, most of whom were working in the San Francisco Bay area on temporary visas for the summer vacation, had been celebrating a friend's 21st birthday on the fourth-floor balcony when the accident occurred, according to local police and Irish government officials.
Berkeley Police Chief Michael Meehan told a news conference about 12 hours after the collapse that there was "no indication of criminal activity or criminal intent." Authorities said they were investigating a number of factors, including the structural integrity of the balcony and whether alcohol may have played a role.
Meehan said police had received a complaint of a loud party at the residence less than an hour before the tragedy.
Thirteen people were on the small balcony when it gave way, plunging 40 feet (12 meters) to the street below, with some victims landing on top of one another, officials said. Three men and three women died, and the seven others remained hospitalized on Tuesday.
Berkeley police spokeswoman Jennifer Coats described the injuries as "very serious and potentially life-threatening."
Pictures from the scene showed the fallen deck pancaked onto a third-story balcony beneath it at the Library Gardens apartment complex, about two blocks from the UC Berkeley campus across the bay from San Francisco.
The balcony, slightly wider than the double-doors leading out to it and no more than 5 feet (1.5 meters) deep, had been rated to safely carry a maximum weight of 60 pounds per square foot (293 kg per sq meter), a city spokesman said, adding there was no requirement for the building owners to post a limit for the number of people it could hold.
Splintered wooden beams and torn insulating material were left visible from where the balcony deck detached from the building's outer wall and fell onto the balcony on the floor below.
No one was on the third-floor balcony at the time, and no one on the ground was hurt, police said.
Following the collapse, authorities declared all similar balconies in the complex off-limits as a precaution.
Phil Grant, the San Francisco-based Irish consul for the U.S. West Coast, said news of the accident had left citizens all over Ireland "frozen in shock and disbelief."
"It's deeply, deeply tragic, and it touches every family in Ireland," he said.
Irish Prime Minister Enda Kenny issued a statement of condolence to the victims' families, saying, "My heart breaks for the parents who lost children this morning."
Speaking to Irish national broadcaster RTE, Irish Foreign Minister Charlie Flanagan called the incident "an appalling tragedy ... a party, a 21st birthday party, turning into tragedy in a moment."
The dead were identified as Ashley Donohoe, 22, the lone American in the group, from Rohnert Park, 50 miles (80 km) north of San Francisco; along with two Irish women - Olivia Burke and Eimear Walsh, both 21; and three Irish men - Eoghan Culligan, Niccolai Shuster, and Lorcan Miller, all 21.
Grant said most of the students were from the Dublin area. The injured were not publicly identified.
The victims were among the thousands of students from Irish universities who travel to the United States on temporary working visas every summer before returning home to complete their studies.
Coats said callers first reported the collapse in the downtown area of the college town at around 12:45 a.m.
Neighbor Jason Biswas, 16, a high school student who lives in the building, said the collapse woke up his parents.
"They thought it was an earthquake until we all looked out the window and realized what happened," he told Reuters, adding that he saw "a bunch of bodies on the ground, most of them not responding."
Bystanders later left flowers outside the building in memory of those killed.
Police and fire department personnel and others were working to determine the cause of the collapse.
Gene St. Onge, an engineer from nearby Oakland, reviewed a picture of the detached balcony at the request of the San Francisco Chronicle and said inadequate waterproofing where the deck meets the building appeared to be a factor.
"This appears to be a classic case," he said. "If the waterproofing is substandard, rainwater can enter the building, causing dry rot, which can destroy the wood members within a short time ... only a few years from construction."
City spokesman Matthai Chakko said construction of the building was completed in 2007, with a final inspection conducted in January of that year.
The building is owned through a real estate fund overseen by the New York-based BlackRock investment-management group.