The prom was supposed to be held Friday night, but it was postponed over the incident.
Instead, students gathered, some in their prom tuxedos and dresses, for a memorial at Walnut Beach in Milford, Conn.
The group released a bunch of purple balloons in Maren's memory.
The students named Maren the school's 2014 prom queen and posted a photo of the teen's unworn prom dress on Twitter.
Classmate Crystal Johnson was at the memorial and said Maren didn't deserve to be killed.
“She had the prom queen type of personality. I just felt she deserved it," she said of the decision to name her prom queen.
Maren died Friday morning after an alleged confrontation with a fellow student, identified by witnesses as Chris Plaskon.
After she rejected his prom invitation, he allegedly threw her down the stairs and stabbed her in the neck with a kitchen knife he brought with him from home.