LaRosa, of Mendham, 18, was a leader and captain of the Minutemen lacrosse team.
"We are calling on the community help support Matt’s family, classmates, teammates, teachers and school officials as they deal with their tragic loss," Morris Sussex Sports wrote in a Thursday morning Facebook post.
"Deepest condolences to the LaRosa family," one person commented. "There is no greater heartbreak."
"[P]rayers, love and support to an amazing family.... we are all behind you," another added.
Visitation will be Sunday, Jan. 5 from 1 to 5 p.m. at the Bailey Funeral Home in Mendham. A funeral service will be held Monday, Jan. 6 at 10:30 a.m., at St. Joseph Church.
A private family interment will follow the funeral service at Hilltop Cemetery.
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