"The class of 2022 gathered this morning to honor the memory of their classmate, Blake Barklage, and to console each other on their loss," the school posted on Facebook Monday afternoon.
Officials say Barklage died of sudden cardiac arrest on Saturday night and no drugs were involved.
Barklage, a senior at La Salle, is being remembered as a good student and athlete.
"In addition to being a good student, a tennis player, member of our Mock Trial team, and active in service at the Triest House, Blake was a varsity soccer manager," read a letter to parents Sunday.
La Salle College High School's soccer team defeated Father Judge on Saturday to win the Philadelphia Catholic League Championship.
"His death followed that team's hard-fought PCL victory, which Blake greatly enjoyed," read a portion of the letter.
In the letter, the school told its students, "We are here for you all now and in the days to come."
Grief counselors are being made available on campus.