Brothers, 16 and 19, Drown at New Jersey School Swimming Pool: 'Unspeakable Tragedy'

Two teenage brothers, one of whom had recently graduated from high school, died after drowning in a New Jersey school pool on Wednesday.

The brothers, 16 and 19, were swimming at the Lincoln Community School pool — which is open to the public at night — around 8:30 p.m. when the tragedy occurred, according to NBC News.

"According to witnesses and the three lifeguards on duty, the two victims were observed to be in distress in the deep end of the pool," the Bayonne Police Department said in a statement, reported WABC-TV.

As one of the lifeguards approached the deep end, "he observed the two victims unable to resurface and entered the pool," the statement continued.

A city official reportedly told NBC New York that their 11-year-old sister was there when they drowned and saw it happen. However, according to NJ.com, a police captain said their younger sister, who is a fourth-grade student, was at the pool, but not with her brothers at the time of the incident.

The Bayonne Police Department did not immediately respond to PEOPLE's request for comment.

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Although life saving measures were initiated after removing the brothers from the pool, they were pronounced dead at Bayonne Medical Center, police said, according to NBC News.

Additional details about the incident, which is currently under investigation, were not immediately shared.

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Bayonne school district Superintendent John Niesz shared the news with the school community late Wednesday.

"Unfortunately, I have very sad news to share with our community in reference to a pool incident at Lincoln Community School pool," Niesz wrote in a letter that was shared on social media. "This evening, two brothers, one a recent graduate of Bayonne High School and the other a current Bayonne High School junior, have passed away."

"Our hearts and prayers go out to the family and to all of our community," Niesz added, sharing that additional counselors would be available at all district schools on Thursday, and that the Lincoln School pool would be closed "until further notice."

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Added Mayor Jimmy Davis in a separate statement, "The City of Bayonne is in mourning tonight, as we learn of the passing of two teenage brothers."

"I ask that we all respect the privacy of the family, as they deal with this unspeakable tragedy," David added.

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Although officials have yet to release their full names, the school district superintendent said in a statement on Thursday that they will be starting a fundraiser "on behalf of the Zheng & Jiang family."

In addition to being investigated by the police, Niesz shared that reports will be "conducted by the school district, school insurance carrier, and Occupational Safety and Health Administration." The school district will also commission an "independent investigation."

"I would like to commend our staff, first responders and administration who were present last evening for their efforts trying to save Mr. Zheng and Mr. Jiang," added the superintendent.