HARTFORD, Conn. -- A 20-year-old college student whose father was killed in the Sept. 11 attacks has died after choking during a pancake-eating contest.

Police said Caitlin Nelson died Sunday, three days after participating in the contest during a fraternities and sororities event at Sacred Heart University, CBS New York reports. She was from Clark, New Jersey, and was a junior majoring in social work at the Roman Catholic school in Fairfield, Connecticut.

“It’s a tragic event that started out as something fun,” said Fairfield police Lt. Bob Kalamaras. ”It was just a tragic accident.”

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When Nelson started choking at the contest, two nursing students immediately began lifesaving measures and were quickly joined by police officers and paramedics, Kalamaras said. She was taken to an area hospital, where she initially was in critical but stable condition, according to police. She was transported to a New York hospital on Friday.

Several thousand people gathered on the Sacred Heart campus Sunday night to remember Nelson and share their grief. A Mass dedicated to her was followed by an impromptu candlelight vigil.

Dozens on the university’s Facebook page expressed sadness over Nelson’s death and posted messages of support.

“We are so sorry for this tragic loss,” one user wrote. “May Caitlin’s family be wrapped in God’s love and have faith they will meet again. May the students find comfort and support in one another.”

“My son called me last night [with] the news,” posted another. “It is so terribly heartbreaking. My prayers are w Caitlin’s family and all of SHU at this sad, heartbreaking time.”

Nelson’s father, James Nelson, was a Port Authority of New York and New Jersey police officer killed in the Sept. 11, 2001 attacks in Manhattan. The 40-year-old died while trying to rescue people trapped in the World Trade Center. His obituary said he was survived by two daughters, 11-year-old Anne and 5-year-old Caitlin.

School officials said counseling services were being provided.

“The SHU community is mourning today,” the school said in a statement Monday. “We ask that during this time you give Caitlin’s family and the members of the SHU community privacy while they grieve.”

According to her LinkedIn page, Caitlin was certified in youth mental health first aid and volunteered at the Resiliency Center of Newtown, a nonprofit group that provides free counseling and other services to people affected by the 2012 shooting at Sandy Hook Elementary School that killed 20 children and six educators.

Funeral services have not been announced.