BERKELEY, Calif. (AP) -- A 21st-birthday party thrown by a group of visiting Irish college students turned tragic early Tuesday when the fifth-floor balcony they were crammed onto collapsed with a sharp crack, spilling them about 50 feet onto the pavement. Six people were killed and seven seriously injured.
Police and fire and building officials were working to figure out why the small balcony broke loose from the stucco apartment house a couple of blocks from the campus of the University of California, Berkeley. But one structural engineer said it may have been overloaded if, as city officials said, it was holding 13 people.
High school student Jason Biswas' family nearby was awakened by the noise.
"They thought there was an earthquake, but then we looked out the window and saw seven or eight people on the ground," the 16-year-old said. "There were piles of blood everywhere."
Five of the dead were 21-year-olds from Ireland who were in the country on so-called J-1 visas that enable young people to work and travel in the U.S. over the summer, while the sixth victim was from California, authorities said.
The accident brought an outpouring of grief in Ireland from the prime minister on down, with the country's consul general in San Francisco calling it a "national tragedy."
Police had gotten a complaint about a loud party in the apartment about an hour before the accident but had not yet arrived when the metal-rail balcony gave way just after 12:30 a.m., spokesman Byron White said. It landed on the fourth-floor balcony just beneath it, leaving the pavement strewn with rubble and the red plastic cups that are practically standard at college parties.
"I just heard a bang and a lot of shouting," said Dan Sullivan, a 21-year-old student from Ireland who was asleep in the five-story building. Mark Neville, another Irish student in the building, said: "I walked out and I saw rubble on the street and a bunch of Irish students crying."
The U.S. government's J-1 program brings 100,000 college students to this country every year, many of them landing jobs at resorts, summer camps and other attractions. The San Francisco Bay area is especially popular with Irish students, about 700 of whom are working and playing here this summer, according to Ireland's Consul General Philip Grant. Many work at Fisherman's Wharf and other tourist sites.
Sinead Loftus, 21, who attends Trinity College Dublin and is living this summer in a different apartment in Berkeley, said Berkeley is "the Irish hub." In fact, she said, "I've heard people complain there are too many people from Ireland here."
"It's student-friendly, it's warm and it's a lot cheaper than San Francisco," she said.
Investigators will look at such things as whether the balcony was built to code, whether it was overloaded and whether rain or other weather weakened it, said Kevin Moore, chairman of the structural standards committee of the Structural Engineers Association of California.
Berkeley officials said the building code would have required the balcony to hold at least 60 pounds per square foot. Its exact dimensions were not released, but Grace Kang, a structural engineer and spokeswoman for Pacific Earthquake Engineering Research Center at Berkeley, said it looked to her to be 4 by 6 feet, or 24 square feet. That would mean it was supposed to hold at least 1,440 pounds.
She said it appeared small for the crowd that had apparently gathered on it, Kang said.
"They were packed like sardines, and then they were moving," Kang said. When people "are moving about a lot or dancing, that impact load may further exacerbate" the strain.
Also, the apartment house appeared to have been wood-frame construction, and the balcony was cantilevered out from the building, with no additional support beneath. Both can make a balcony more vulnerable to dry rot and weathering in general, Kang said.
In the meantime, city inspectors barred use of the building's other balconies while they are checked for safety.
The Library Gardens apartment complex, completed in 2007, is in a lively part of downtown Berkeley close to the campus and is a popular place for students to live. Several tenants reached by telephone said it is well-maintained.
Berkeley Police Chief Michael Neeham said the response to the noise complaint had been given a lower priority after police received a call of shots fired elsewhere.
The building is owned by BlackRock, the largest asset management fund in the U.S., according to city officials, and managed by Greystar Management, whose website says it operates more than 400,000 units in the U.S. and abroad.
In a statement, Greystar extended condolences to the victims' families and added: "The safety of our residents is our highest priority and we will be working with an independent structural engineer and local authorities to determine the cause of the accident."
On the closed street below, a shrine was growing: flowers, a pack of cigarettes, a Cal Berkeley banner, condolence notes. Victims' relatives were expected to begin arriving from Ireland on Tuesday night.
The dead were identified as Ashley Donohoe, 22, of Rohnert Park, California, and Ireland's Olivia Burke, Eoghan Culligan, Niccolai Schuster, Lorcan Miller and Eimear Walsh. The Irish students attended various colleges in Dublin.
"My heart breaks for the parents who lost children this morning, and I can only imagine the fear in the hearts of other parents whose children are in California this summer as they seek to contact them now," Irish Prime Minister Enda Kenny told lawmakers in Dublin.
"It is truly terrible to have such a serious and sad incident take place at the beginning of a summer of adventure and opportunity for so many young people on J-1 visas in the U.S."
A 2010 Associated Press investigation of the J-1 program and the companies that arrange the visits found that many students paid thousands of dollars to come to the U.S., only to learn the jobs they were promised didn't exist. Some had to share beds in crowded houses or filthy apartments.
Following the investigation, the State Department tightened its rules governing participating businesses.
Associated Press writers Paul Elias, Ellen Knickmeyer and Lisa Leff in San Francisco, Christopher Weber in Los Angeles and Bob Seavey in Phoenix contributed to this report.