The deaths of six students, five of whom were visiting from Ireland, have sent family, friends and strangers into mourning. In Ireland, officials ordered the national flag to fly at half staff, and in the Bay Area, questions abound about how an apartment complex’s fourth-floor balcony plummeted to the ground early Tuesday morning.

Of the six who died, Olivia Burke, Eimear Walsh, Lorcan Miller, Niccolai Schuster and Eoghan Culligan were 21-year-old students visiting from Ireland for the summer on J-1 visas, and Ashley Donohoe, 22, was an Irish American student at Sonoma State University.

The collapse left seven others in the hospital with serious injuries. An investigation into the cause of the collapse is ongoing, but multiple experts have pointed to dry rot.

More than 100 students attended a candlelight vigil Wednesday night near Berkeley High School. The students gathered in a large circle as Father Ivan Tou of the Newman Hall-Holy Spirit Parish in Berkeley led the group in a Catholic prayer.

Those honored at the vigil include Donohoe, who was a rising senior at Sonoma State in Rohnert Park, California, and graduated from Rancho Cotate High School, also located in Rohnert Park, in 2011. While in college, she volunteered as the assistant coach for her high school’s soccer team, according to Josh Wilson, assistant principal of Rancho Cotate High.

Wilson said that in high school, Donohoe was a “leader on campus with a big peer group, a lot of friends.” He described the Rancho Cotate High community as “devastated,” saying, “Our hearts go out to the family, and she will be sorely missed.”

At Sonoma State, Donohoe studied biology and was a member of the Pre-Health Professions Club. Her friend and classmate Alec Estacio, who graduated from Sonoma State in 2014, remembers her as “always full of life and really positive all the time.”

“She was that person that knew everyone and became best friends with everyone,” Estacio said. “She was that person who you may not remember her name, but she always knew yours, and she was that person who made you feel special all the time.”

According to Estacio, Donohoe aspired to be a doctor in Ireland and planned annual trips to the Dublin area to visit Burke, her cousin, who also died in the collapse along with Burke’s friend Walsh.

A colleague remembers Burke and Walsh for being hardworking and down to earth. They attended Loreto College, a private Catholic secondary school in Foxrock, Dublin.

“We are deeply saddened and shocked by the events that took place,” said Loreto College officials in a statement released on the school’s website. “We offer our deepest sympathies to the families of Olivia and Eimear, and to the families of the other students who died.”

After graduating from Loreto College, Walsh went on to study medicine at University College Dublin, while Burke studied entrepreneurship and management at the Dun Laoghaire Institute of Art, Design and Technology, also in Dublin.

In addition to attending school together, Walsh and Burke both had jobs this summer working in San Francisco at Hana Zen, a sushi restaurant on Pier 39 that is popular among tourists.

A co-worker described them as sweet girls who were excited and grateful to be in the United States for the summer. They were good with customers, and Walsh was even promoted from hostess to server after only two weeks at the restaurant, the employee said.

Like Burke and Walsh, Miller is also remembered for being hardworking. He, too, studied medicine at University College Dublin, and the university recognized him as an entrance scholar, a title awarded to students who perform well on their high school final exams.

Teachers recalled that he was “exceptionally likeable” and “academically gifted with a command of Irish and French,” according to a statement released by St. Andrew’s College in Dublin, where Miller completed his secondary education.

In addition to playing hockey and singing in musical theater productions at St. Andrew’s, Miller was also deputy head boy, a peer-elected position that reserved him a seat on the student council, according to the statement. As deputy, he acted as a mediary between students and college officials.

In his free time, Miller was a volunteer umpire for University College Dublin and played hockey at the school. Jonathan Codd, who played hockey with Miller for two years, wrote in the book of condolences created by the university that Miller “was an incredibly smart lad who was always so friendly.”

Miller recently began training as a server at Bubba Gump Shrimp Co. in San Francisco. His trainer, Gregory Edquid, described him as one of his best trainees and a quick learner who always came prepared with a positive attitude.

Also a student at University College Dublin, Schuster previously attended St. Mary’s College, an all-male school in the Rathmines district of Dublin. He was originally from Terenure, a Dublin suburb. In 2010, he taught English to children and took classes in Ghana through the Ghana Immersion Project.

Richard McElligott, who taught Schuster at University College Dublin’s School of History and Archives, described him as “a wonderful and polite young man” on the university’s online book of condolences for the students who died in the collapse.

“He was and always will be an absolute beacon of happiness and life and showed everyone that life was there to be enjoyed,” wrote fellow University College Dublin student Ken Murray in the online book.

Culligan, who also died in the collapse, was a former classmate of Schuster’s at St. Mary’s and studied at the Dublin Institute of Technology, according to his Facebook profile. He lived in Rathfarnham, a suburb of Dublin.

“The thoughts and prayers of everybody in the St Mary’s Community are with the families of Niccolai and Eoghan, and the other Irish youngsters who died or were injured in the heartbreaking accident in the United States on Tuesday,” said St. Mary’s in a statement.

Culligan was an avid player of Gaelic football, and he played with the Ballyboden St. Enda’s GAA club since childhood.

“(Culligan) was very popular with his teammates and this tragic news is keenly felt by all members of our Club, but especially by those players and mentors who knew him well,” said Ballyboden officials in a post on the club’s website.

“(Culligan) was always in good spirits in school and will be so dearly missed,” wrote former classmate Kayleigh McCarthy in the book of condolences.

Cian Coughlan, an Irish citizen who is also visiting the United States on a J-1 visa, said he went to the Wednesday night vigil despite not knowing anyone directly involved in the balcony collapse.

“Came to show support, I suppose,” he said. “It’s an Irish thing. Even if I don’t know them, the more people that come show that support is there. Irish people just come together in times of strife.”

Staff writer Ethan Walker contributed to this report.