BERKELEY, Calif. — They come by the thousands — Irish students on work visas, many flocking to the West Coast to work in summer jobs by day and to enjoy the often raucous life in a college town at night. It was, for many, a rite of passage, one last summer to enjoy travel abroad before beginning a career.

But the work-visa program that allowed for the exchanges has in recent years become not just a source of aspiration, but also a source of embarrassment for Ireland, marked by a series of high-profile episodes involving drunken partying and the wrecking of apartments in places like San Francisco and Santa Barbara.

Early Tuesday, 13 people, most of them young Irish students here on the visa program, were crowded onto a fourth-floor balcony off Unit 405 for what neighbors described as a loud party when the balcony collapsed, sending people tumbling onto the street below.

Six people were killed; five were Irish and the sixth had dual Irish-American citizenship, according to the Irish Embassy. Three of the dead were men, three were women, and all were in their 20s. At least seven others suffered injuries, some serious.